Mammoth Uncensored Word List:
39 words ending with cy, 13 letters long

adiathermancy circumjacency consenescency constringency convalescency dactyliomancy defervescency effervescency gyrofrequency inappropriacy incandescency inconsistency inconveniency indeterminacy insufficiency intermittency intransigency multicurrency nonabsorbency noncompetency nondegeneracy nonefficiency nonlegitimacy nontransiency pentachromacy petrocurrency postemergency premalignancy preponderancy quadrivalency recalcitrancy recrudescency retromingency sanguinolency tetrachromacy thalassocracy thalattocracy transcendency transmittancy