tails vs dress suit

tails and dress suit both are nouns.

Word	Noun	Adjective	Verb	Adverb
tails	Yes	No	No	No
dress suit	Yes	No	No	No

As nouns, tails and dress suit are synonyms defined as:

tails and dress suit: formalwear consisting of full evening dress for men

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

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