tails vs tailcoat

tails and tailcoat both are nouns.

Word	Noun	Adjective	Verb	Adverb
tails	Yes	No	No	No
tailcoat	Yes	No	No	No

As nouns, tails and tailcoat are synonyms defined as:

Other synonyms of tails include dress suit, full dress, tail coat, white tie, white tie and tails.

tails (noun)	tailcoat (noun)
formalwear consisting of full evening dress for men	formalwear consisting of full evening dress for men