"alternates" in the noun sense
1. surrogate, alternate, replacement
someone who takes the place of another person
"alternates" in the verb sense
1. alternate, jump
go back and forth swing back and forth between two states or conditions
2. alternate
exchange people temporarily to fulfill certain jobs and functions
3. understudy, alternate
be an understudy or alternate for a role
4. interchange, tack, switch, alternate, flip, flip-flop
reverse (a direction, attitude, or course of action)
5. alternate, take turns
do something in turns
"We take turns on the night shift"
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License