tailcoat vs tail coat

tailcoat and tail coat both are nouns.

Word	Noun	Adjective	Verb	Adverb
tailcoat	Yes	No	No	No
tail coat	Yes	No	No	No

As nouns, tailcoat and tail coat are synonyms defined as:

tailcoat and tail coat: formalwear consisting of full evening dress for men

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

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