sideboob vs breast

sideboob and breast both are nouns.

Word	Noun	Adjective	Verb	Adverb
sideboob	Yes	No	No	No
breast	Yes	No	Yes	No

As nouns, breast is a hypernym of sideboob; that is, breast is a word with a broader meaning than sideboob:

sideboob: A breast exposed from the side
breast: either of two soft fleshy milk-secreting glandular organs on the chest of a woman

Other hypernyms of sideboob include boob, bosom, knocker, tit, titty.

sideboob (noun)	breast (noun)
A breast exposed from the side	the part of an animal's body that corresponds to a person's chest
	either of two soft fleshy milk-secreting glandular organs on the chest of a woman
	the front of the trunk from the neck to the abdomen
	meat carved from the breast of a fowl

sideboob (verb)	breast (verb)
	confront bodily
	reach the summit (of a mountain)
	meet at breast level