Definition of proliferation

"proliferation" in the noun sense

1. proliferation

growth by the rapid multiplication of parts

2. proliferation

a rapid increase in number (especially a rapid increase in the number of deadly weapons

"the proliferation of nuclear weapons"

Source: WordNet® (An amazing lexical database of English)

Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.

View WordNet® License

↑

proliferation in Scrabble®

The word proliferation is playable in Scrabble®, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.

Scrabble® Letter Score: 18

Highest Scoring Scrabble® Plays In The Letters proliferation:

PROLIFERATION

(180)

PROLIFERATION

(180)

Seven Letter Word Alert: (95 words)

aileron, airfoil, airlift, airline, airport, elation, fainter, filiate, fireant, firelit, firepan, firepit, firepot, fleapit, flirter, floater, foliate, forlorn, frailer, frontal, inertia, inflate, latrine, lintier, liriope, loftier, loonier, loopier, nepotal, niftier, oilfire, opaline, operant, oration, ornater, otarine, painter, partner, pentail, pertain, pinfire, pinitol, pintail, plainer, planter, platoon, pointer, polaron, politer, poofier, portion, praetor, prairie, praline, printer, profane, profile, proline, pronate, proofer, prorate, protean, protein, rainier, ratline, realtor, refloat, refrain, reliant, repaint, repilot, replait, replant, repoint, reprint, reproof, retinal, retinol, retrain, retrial, roilier, tailfin, tailpin, terrain, tinfoil, toenail, topline, toprail, trailer, trainer, trefoil, trenail, trifler, tripole, trooper

All Scrabble® Plays For The Word proliferation

PROLIFERATION

(180)

PROLIFERATION

(180)

PROLIFERATION

(120)

PROLIFERATION

(120)

PROLIFERATION

(92)

PROLIFERATION

(92)

PROLIFERATION

(88)

PROLIFERATION

(88)

PROLIFERATION

(80)

PROLIFERATION

(80)

PROLIFERATION

(76)

PROLIFERATION

(72)

PROLIFERATION

(72)

PROLIFERATION

(72)

PROLIFERATION

(60)

PROLIFERATION

(56)

PROLIFERATION

(44)

PROLIFERATION

(40)

PROLIFERATION

(30)

PROLIFERATION

(30)

PROLIFERATION

(25)

PROLIFERATION

(24)

PROLIFERATION

(24)

PROLIFERATION

(22)

The 200 Highest Scoring Scrabble® Plays For Words Using The Letters In proliferation

PROLIFERATION

(180)

PROLIFERATION

(180)

PROLIFERATION

(120)

PROLIFERATION

(120)

PROOFER

(98 = 48 + 50)

FIREPAN

(98 = 48 + 50)

FLEAPIT

(98 = 48 + 50)

FIREPAN

(98 = 48 + 50)

PROFANE

(98 = 48 + 50)

PINFIRE

(98 = 48 + 50)

PINFIRE

(98 = 48 + 50)

PROFANE

(98 = 48 + 50)

PROFANE

(98 = 48 + 50)

PROFILE

(98 = 48 + 50)

FIREPOT

(98 = 48 + 50)

FIREPOT

(98 = 48 + 50)

POOFIER

(98 = 48 + 50)

REPROOF

(98 = 48 + 50)

POOFIER

(98 = 48 + 50)

PROOFER

(98 = 48 + 50)

REPROOF

(98 = 48 + 50)

POOFIER

(98 = 48 + 50)

FIREPIT

(98 = 48 + 50)

FIREPIT

(98 = 48 + 50)

PINFIRE

(98 = 48 + 50)

PROFILE

(98 = 48 + 50)

FLEAPIT

(98 = 48 + 50)

PROFILE

(98 = 48 + 50)

FIREPIT

(95 = 45 + 50)

REPROOF

(95 = 45 + 50)

PROFILE

(95 = 45 + 50)

PROFANE

(95 = 45 + 50)

PROOFER

(95 = 45 + 50)

FIREPAN

(95 = 45 + 50)

FIREPOT

(95 = 45 + 50)

POOFIER

(95 = 45 + 50)

FLEAPIT

(95 = 45 + 50)

PINFIRE

(95 = 45 + 50)

TINFOIL

(92 = 42 + 50)

AIRFOIL

(92 = 42 + 50)

INFLATE

(92 = 42 + 50)

FIRELIT

(92 = 42 + 50)

FAINTER

(92 = 42 + 50)

TINFOIL

(92 = 42 + 50)

OILFIRE

(92 = 42 + 50)

FORLORN

(92 = 42 + 50)

TREFOIL

(92 = 42 + 50)

TREFOIL

(92 = 42 + 50)

TAILFIN

(92 = 42 + 50)

TRIFLER

(92 = 42 + 50)

FIREANT

(92 = 42 + 50)

TRIFLER

(92 = 42 + 50)

AIRFOIL

(92 = 42 + 50)

FRAILER

(92 = 42 + 50)

OILFIRE

(92 = 42 + 50)

FRONTAL

(92 = 42 + 50)

FOLIATE

(92 = 42 + 50)

REFLOAT

(92 = 42 + 50)

PROLIFERATION

(92)

FLIRTER

(92 = 42 + 50)

NIFTIER

(92 = 42 + 50)

PROLIFERATION

(92)

FILIATE

(92 = 42 + 50)

REFRAIN

(92 = 42 + 50)

LOFTIER

(92 = 42 + 50)

AIRLIFT

(92 = 42 + 50)

FLOATER

(92 = 42 + 50)

FRAILER

(90 = 40 + 50)

REFRAIN

(90 = 40 + 50)

FAINTER

(90 = 40 + 50)

LOFTIER

(90 = 40 + 50)

NIFTIER

(90 = 40 + 50)

AIRLIFT

(90 = 40 + 50)

FIREANT

(90 = 40 + 50)

FLIRTER

(90 = 40 + 50)

FORLORN

(90 = 40 + 50)

REFLOAT

(90 = 40 + 50)

FILIATE

(90 = 40 + 50)

TRIFLER

(90 = 40 + 50)

AIRFOIL

(90 = 40 + 50)

FLOATER

(90 = 40 + 50)

TAILFIN

(90 = 40 + 50)

FIRELIT

(90 = 40 + 50)

PROOFER

(90 = 40 + 50)

TINFOIL

(90 = 40 + 50)

OILFIRE

(90 = 40 + 50)

FOLIATE

(90 = 40 + 50)

INFLATE

(90 = 40 + 50)

FRONTAL

(90 = 40 + 50)

TREFOIL

(90 = 40 + 50)

FLEAPIT

(89 = 39 + 50)

POOFIER

(89 = 39 + 50)

FIREPAN

(89 = 39 + 50)

PINFIRE

(89 = 39 + 50)

FLEAPIT

(89 = 39 + 50)

PROFANE

(89 = 39 + 50)

POOFIER

(89 = 39 + 50)

FIREPAN

(89 = 39 + 50)

FLEAPIT

(89 = 39 + 50)

PROOFER

(89 = 39 + 50)

PROOFER

(89 = 39 + 50)

PROFILE

(89 = 39 + 50)

FIREPAN

(89 = 39 + 50)

PINFIRE

(89 = 39 + 50)

FIREPAN

(89 = 39 + 50)

PINFIRE

(89 = 39 + 50)

PROFILE

(89 = 39 + 50)

PROOFER

(89 = 39 + 50)

FIREPAN

(89 = 39 + 50)

FIREPIT

(89 = 39 + 50)

PINFIRE

(89 = 39 + 50)

PROOFER

(89 = 39 + 50)

PROFANE

(89 = 39 + 50)

FLEAPIT

(89 = 39 + 50)

POOFIER

(89 = 39 + 50)

PROFANE

(89 = 39 + 50)

PROOFER

(89 = 39 + 50)

FLEAPIT

(89 = 39 + 50)

PROFANE

(89 = 39 + 50)

POOFIER

(89 = 39 + 50)

REPROOF

(89 = 39 + 50)

FIREPIT

(89 = 39 + 50)

FIREPIT

(89 = 39 + 50)

FIREPOT

(89 = 39 + 50)

FIREPOT

(89 = 39 + 50)

PROFILE

(89 = 39 + 50)

FIREPIT

(89 = 39 + 50)

FIREPOT

(89 = 39 + 50)

FIREPOT

(89 = 39 + 50)

PROOFER

(89 = 39 + 50)

FIREPIT

(89 = 39 + 50)

FIREPOT

(89 = 39 + 50)

FIREPOT

(89 = 39 + 50)

REPROOF

(89 = 39 + 50)

REPROOF

(89 = 39 + 50)

REPROOF

(89 = 39 + 50)

FIREPIT

(89 = 39 + 50)

POOFIER

(89 = 39 + 50)

PINFIRE

(89 = 39 + 50)

PROFILE

(89 = 39 + 50)

PROFANE

(89 = 39 + 50)

REPROOF

(89 = 39 + 50)

PROFILE

(89 = 39 + 50)

FLEAPIT

(89 = 39 + 50)

FIREPAN

(89 = 39 + 50)

REPROOF

(89 = 39 + 50)

PROLIFERATION

(88)

PROLIFERATION

(88)

POLITER

(86 = 36 + 50)

REPLANT

(86 = 36 + 50)

REPOINT

(86 = 36 + 50)

PLAINER

(86 = 36 + 50)

LOFTIER

(86 = 36 + 50)

PENTAIL

(86 = 36 + 50)

PLAINER

(86 = 36 + 50)

OPALINE

(86 = 36 + 50)

PENTAIL

(86 = 36 + 50)

PLANTER

(86 = 36 + 50)

LOOPIER

(86 = 36 + 50)

FLEAPIT

(86 = 36 + 50)

REPLANT

(86 = 36 + 50)

AIRPORT

(86 = 36 + 50)

PRALINE

(86 = 36 + 50)

PRORATE

(86 = 36 + 50)

LOOPIER

(86 = 36 + 50)

REPROOF

(86 = 36 + 50)

PAINTER

(86 = 36 + 50)

REPROOF

(86 = 36 + 50)

OPERANT

(86 = 36 + 50)

PROFILE

(86 = 36 + 50)

PROTEIN

(86 = 36 + 50)

LIRIOPE

(86 = 36 + 50)

PRINTER

(86 = 36 + 50)

PINTAIL

(86 = 36 + 50)

PARTNER

(86 = 36 + 50)

PRINTER

(86 = 36 + 50)

PARTNER

(86 = 36 + 50)

PROTEIN

(86 = 36 + 50)

OPERANT

(86 = 36 + 50)

PAINTER

(86 = 36 + 50)

PROTEAN

(86 = 36 + 50)

TAILFIN

(86 = 36 + 50)

AIRPORT

(86 = 36 + 50)

REPOINT

(86 = 36 + 50)

PRALINE

(86 = 36 + 50)

AIRLIFT

(86 = 36 + 50)

POLARON

(86 = 36 + 50)

REPRINT

(86 = 36 + 50)

POLITER

(86 = 36 + 50)

PLANTER

(86 = 36 + 50)

POLARON

(86 = 36 + 50)

PINTAIL

(86 = 36 + 50)

PRORATE

(86 = 36 + 50)

AIRPORT

(86 = 36 + 50)

FLEAPIT

(86 = 36 + 50)

REPRINT

(86 = 36 + 50)

LIRIOPE

(86 = 36 + 50)

PROTEAN

(86 = 36 + 50)

TAILPIN

(86 = 36 + 50)

PROFANE

(86 = 36 + 50)

Your Best
Scrabble
Plays Legendary
Scrabble
Plays

↑

proliferation in Words With Friends™

The word proliferation is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.

Words With Friends™ Letter Score: 21

Highest Scoring Words With Friends™ Play In The Letters proliferation:

PROLIFERATION

(279)

Seven Letter Word Alert: (95 words)

All Words With Friends™ Plays For The Word proliferation

PROLIFERATION

(279)

PROLIFERATION

(225)

PROLIFERATION

(225)

PROLIFERATION

(162)

PROLIFERATION

(150)

PROLIFERATION

(104)

PROLIFERATION

(100)

PROLIFERATION

(96)

PROLIFERATION

(92)

PROLIFERATION

(84)

PROLIFERATION

(84)

PROLIFERATION

(84)

PROLIFERATION

(62)

PROLIFERATION

(54)

PROLIFERATION

(50)

PROLIFERATION

(31)

PROLIFERATION

(30)

PROLIFERATION

(28)

PROLIFERATION

(28)

PROLIFERATION

(27)

PROLIFERATION

(26)

PROLIFERATION

(24)

PROLIFERATION

(24)

PROLIFERATION

(24)

The 200 Highest Scoring Words With Friends™ Plays Using The Letters In proliferation

PROLIFERATION

(279)

PROLIFERATION

(225)

PROLIFERATION

(225)

PROLIFERATION

(162)

PROLIFERATION

(150)

PROFILE

(113 = 78 + 35)

PROFANE

(113 = 78 + 35)

FIREPAN

(113 = 78 + 35)

PINFIRE

(113 = 78 + 35)

PINFIRE

(107 = 72 + 35)

FLEAPIT

(107 = 72 + 35)

FLEAPIT

(107 = 72 + 35)

PROFANE

(107 = 72 + 35)

PROFANE

(107 = 72 + 35)

TAILFIN

(107 = 72 + 35)

PENTAIL

(107 = 72 + 35)

PROFILE

(107 = 72 + 35)

PROFILE

(107 = 72 + 35)

NEPOTAL

(107 = 72 + 35)

PINITOL

(107 = 72 + 35)

TAILPIN

(107 = 72 + 35)

FIREPAN

(107 = 72 + 35)

POLARON

(107 = 72 + 35)

OPALINE

(107 = 72 + 35)

PINTAIL

(107 = 72 + 35)

PINFIRE

(107 = 72 + 35)

REPROOF

(104 = 69 + 35)

FIREPIT

(104 = 69 + 35)

LOFTIER

(104 = 69 + 35)

POOFIER

(104 = 69 + 35)

FILIATE

(104 = 69 + 35)

NIFTIER

(104 = 69 + 35)

FIREPIT

(104 = 69 + 35)

FIREPOT

(104 = 69 + 35)

PROOFER

(104 = 69 + 35)

PROLIFERATION

(104)

FIREPOT

(104 = 69 + 35)

POOFIER

(104 = 69 + 35)

REPROOF

(104 = 69 + 35)

POLITER

(104 = 69 + 35)

TRIPOLE

(104 = 69 + 35)

FOLIATE

(104 = 69 + 35)

PROOFER

(104 = 69 + 35)

AIRLIFT

(104 = 69 + 35)

POOFIER

(104 = 69 + 35)

PINFIRE

(101 = 66 + 35)

PLATOON

(101 = 66 + 35)

PINFIRE

(101 = 66 + 35)

PROFANE

(101 = 66 + 35)

TINFOIL

(101 = 66 + 35)

PROFANE

(101 = 66 + 35)

FIREPAN

(101 = 66 + 35)

FORLORN

(101 = 66 + 35)

PROFANE

(101 = 66 + 35)

FRONTAL

(101 = 66 + 35)

INFLATE

(101 = 66 + 35)

PROLINE

(101 = 66 + 35)

TOPLINE

(101 = 66 + 35)

TINFOIL

(101 = 66 + 35)

REPLANT

(101 = 66 + 35)

PRALINE

(101 = 66 + 35)

FLEAPIT

(101 = 66 + 35)

PROFILE

(101 = 66 + 35)

PLANTER

(101 = 66 + 35)

PLAINER

(101 = 66 + 35)

PROFILE

(101 = 66 + 35)

PINFIRE

(101 = 66 + 35)

PROFILE

(101 = 66 + 35)

PROLIFERATION

(100)

TREFOIL

(98 = 63 + 35)

TRIPOLE

(98 = 63 + 35)

FIREPIT

(98 = 63 + 35)

REPAINT

(98 = 63 + 35)

POINTER

(98 = 63 + 35)

POOFIER

(98 = 63 + 35)

FIREPOT

(98 = 63 + 35)

PAINTER

(98 = 63 + 35)

TRIFLER

(98 = 63 + 35)

PORTION

(98 = 63 + 35)

OPERANT

(98 = 63 + 35)

REPROOF

(98 = 63 + 35)

TOPRAIL

(98 = 63 + 35)

PRONATE

(98 = 63 + 35)

REPOINT

(98 = 63 + 35)

TRIFLER

(98 = 63 + 35)

TREFOIL

(98 = 63 + 35)

PARTNER

(98 = 63 + 35)

PROOFER

(98 = 63 + 35)

FIREANT

(98 = 63 + 35)

REFRAIN

(98 = 63 + 35)

OILFIRE

(98 = 63 + 35)

FLIRTER

(98 = 63 + 35)

FAINTER

(98 = 63 + 35)

PROTEAN

(98 = 63 + 35)

PROTEIN

(98 = 63 + 35)

LIRIOPE

(98 = 63 + 35)

AIRFOIL

(98 = 63 + 35)

POOFIER

(98 = 63 + 35)

FLOATER

(98 = 63 + 35)

REPILOT

(98 = 63 + 35)

LOOPIER

(98 = 63 + 35)

OILFIRE

(98 = 63 + 35)

FIRELIT

(98 = 63 + 35)

LOOPIER

(98 = 63 + 35)

AIRFOIL

(98 = 63 + 35)

PERTAIN

(98 = 63 + 35)

REPRINT

(98 = 63 + 35)

POOFIER

(98 = 63 + 35)

FRAILER

(98 = 63 + 35)

REFLOAT

(98 = 63 + 35)

PRINTER

(98 = 63 + 35)

REPLAIT

(98 = 63 + 35)

PROLIFERATION

(96)

PLATOON

(95 = 60 + 35)

OPALINE

(95 = 60 + 35)

PINTAIL

(95 = 60 + 35)

PROLINE

(95 = 60 + 35)

OPALINE

(95 = 60 + 35)

PRALINE

(95 = 60 + 35)

PLANTER

(95 = 60 + 35)

PRAIRIE

(95 = 60 + 35)

FLEAPIT

(95 = 60 + 35)

PENTAIL

(95 = 60 + 35)

TINFOIL

(95 = 60 + 35)

FORLORN

(95 = 60 + 35)

TROOPER

(95 = 60 + 35)

POLARON

(95 = 60 + 35)

PRORATE

(95 = 60 + 35)

TOPLINE

(95 = 60 + 35)

AIRPORT

(95 = 60 + 35)

PRAETOR

(95 = 60 + 35)

AIRPORT

(95 = 60 + 35)

INFLATE

(95 = 60 + 35)

FRONTAL

(95 = 60 + 35)

PROLINE

(95 = 60 + 35)

PLANTER

(95 = 60 + 35)

PLAINER

(95 = 60 + 35)

TINFOIL

(95 = 60 + 35)

PRALINE

(95 = 60 + 35)

REPLANT

(95 = 60 + 35)

PINITOL

(95 = 60 + 35)

FILIATE

(92 = 57 + 35)

OILFIRE

(92 = 57 + 35)

FIRELIT

(92 = 57 + 35)

AIRLIFT

(92 = 57 + 35)

PROTEAN

(92 = 57 + 35)

AIRFOIL

(92 = 57 + 35)

PARTNER

(92 = 57 + 35)

AIRFOIL

(92 = 57 + 35)

TRIPOLE

(92 = 57 + 35)

PROTEIN

(92 = 57 + 35)

FRAILER

(92 = 57 + 35)

PERTAIN

(92 = 57 + 35)

TRIFLER

(92 = 57 + 35)

PRINTER

(92 = 57 + 35)

FLIRTER

(92 = 57 + 35)

TRIFLER

(92 = 57 + 35)

POINTER

(92 = 57 + 35)

TREFOIL

(92 = 57 + 35)

PAINTER

(92 = 57 + 35)

TREFOIL

(92 = 57 + 35)

OILFIRE

(92 = 57 + 35)

PRONATE

(92 = 57 + 35)

POLITER

(92 = 57 + 35)

LIRIOPE

(92 = 57 + 35)

FLOATER

(92 = 57 + 35)

OPERANT

(92 = 57 + 35)

PROLIFERATION

(92)

LOOPIER

(92 = 57 + 35)

FOLIATE

(92 = 57 + 35)

TRIPOLE

(92 = 57 + 35)

FAINTER

(92 = 57 + 35)

LOOPIER

(92 = 57 + 35)

FIREANT

(92 = 57 + 35)

PORTION

(92 = 57 + 35)

FLEAPIT

(91 = 56 + 35)

PROFILE

(91 = 56 + 35)

PROFILE

(91 = 56 + 35)

PROFANE

(91 = 56 + 35)

PROFANE

(91 = 56 + 35)

FIREPAN

(91 = 56 + 35)

FLEAPIT

(91 = 56 + 35)

PROFANE

(91 = 56 + 35)

FIREPAN

(91 = 56 + 35)

PINFIRE

(91 = 56 + 35)

PROFILE

(91 = 56 + 35)

PINFIRE

(91 = 56 + 35)

FIREPAN

(91 = 56 + 35)

PINFIRE

(91 = 56 + 35)

FLEAPIT

(91 = 56 + 35)

FRONTAL

(89 = 54 + 35)

PINITOL

(89 = 54 + 35)

FORLORN

(89 = 54 + 35)

FIREPAN

(89 = 54 + 35)

FIREPAN

(89 = 54 + 35)

INFLATE

(89 = 54 + 35)

FIREPAN

(89 = 54 + 35)

AIRPORT

(89 = 54 + 35)

NEPOTAL

(89 = 54 + 35)

POLARON

(89 = 54 + 35)

Legendary
Words With Friends
Plays Your Best
Words With Friends
Plays

↑

Words within the letters of proliferation

2 letter words in proliferation (22 words)

ai an ar at ef el en fa if in it la no of on or pa pe pi re ta to

3 letter words in proliferation (85 words)

aft ail air ale ant ape apt are art ate ear eat elf eon era err eta fan far fat fen fin fir fit foe fop for fro ion ire lap lea let lie lip lit loo lop lot nap net nil nip nit nor not oaf oar oat oft oil one opt ore pal pan par pat pea pen per pet pie pin pit pot ran rap rat ref rip roe rot tan tap tar tea ten tie tin tip toe ton too top

4 letter words in proliferation (184 words)

5 letter words in proliferation (144 words)

9 letter words in proliferation (13 words)

epilation foliation forepoint interloop nailproof operation perforant polariton portioner rainproof reflation reptilian tearproof

10 letter words in proliferation (3 words)

fortepiano peroration prefrontal

11 letter words in proliferation (3 words)

apoferritin interfoliar perforation

13 letter words in proliferation (1 word)

proliferation

proliferation + 1 blank (1 word)

proliferations

proliferation + 2 blanks (2 words)

perfluorination reproliferation

↑

Words containing the sequence proliferation

Words that start with proliferation (2 words)

proliferation proliferations

Words with proliferation in them (3 words)

proliferation overproliferations reproliferations

Words that end with proliferation (4 words)

nonproliferation overproliferation proliferation reproliferation

↑

Word Growth involving proliferation

Shorter words in proliferation

era

if life lifer

on ion ration

at rat ratio ration

Longer words containing proliferation

nonproliferation

overproliferation overproliferations

proliferations overproliferations

proliferations reproliferations

reproliferation reproliferations

Definition of proliferation

"proliferation" in the noun sense

1. proliferation

2. proliferation

proliferation in Scrabble®

Scrabble® Letter Score: 18

Highest Scoring Scrabble® Plays In The Letters proliferation:

Seven Letter Word Alert: (95 words)

All Scrabble® Plays For The Word proliferation

The 200 Highest Scoring Scrabble® Plays For Words Using The Letters In proliferation

proliferation in Words With Friends™

Words With Friends™ Letter Score: 21

Highest Scoring Words With Friends™ Play In The Letters proliferation:

Seven Letter Word Alert: (95 words)

All Words With Friends™ Plays For The Word proliferation

The 200 Highest Scoring Words With Friends™ Plays Using The Letters In proliferation

Words within the letters of proliferation

2 letter words in proliferation (22 words)

3 letter words in proliferation (85 words)

4 letter words in proliferation (184 words)

5 letter words in proliferation (144 words)

6 letter words in proliferation (125 words)

7 letter words in proliferation (95 words)

8 letter words in proliferation (55 words)

9 letter words in proliferation (13 words)

10 letter words in proliferation (3 words)

11 letter words in proliferation (3 words)

13 letter words in proliferation (1 word)

proliferation + 1 blank (1 word)

proliferation + 2 blanks (2 words)

Words containing the sequence proliferation

Words that start with proliferation (2 words)

Words with proliferation in them (3 words)

Words that end with proliferation (4 words)

Word Growth involving proliferation

Shorter words in proliferation

Longer words containing proliferation