sexually transmitted disease vs STD

sexually transmitted disease and STD both are nouns.

Word	Noun	Adjective	Verb	Adverb
sexually transmitted disease	Yes	No	No	No
STD	Yes	No	No	No

As nouns, sexually transmitted disease and STD are synonyms defined as:

sexually transmitted disease and STD: a communicable infection transmitted by sexual intercourse or genital contact

Other synonyms of sexually transmitted disease include Cupid's disease, Cupid's itch, dose, social disease, VD, venereal disease, venereal infection, Venus's curse.

sexually transmitted disease (noun)	STD (noun)
a communicable infection transmitted by sexual intercourse or genital contact	a doctor's degree in theology in the pontifical university system of the Catholic church
	a communicable infection transmitted by sexual intercourse or genital contact