tranquilizer vs tranquilliser

tranquilizer and tranquilliser both are nouns.

Word	Noun	Adjective	Verb	Adverb
tranquilizer	Yes	No	No	No
tranquilliser	Yes	No	No	No

As nouns, tranquilizer and tranquilliser are synonyms defined as:

tranquilizer and tranquilliser: a drug used to reduce stress or tension without reducing mental clarity

Other synonyms of tranquilizer include antianxiety agent, ataractic, ataractic agent, ataractic drug, tranquillizer.

tranquilizer (noun)	tranquilliser (noun)
a drug used to reduce stress or tension without reducing mental clarity	a drug used to reduce stress or tension without reducing mental clarity