c. 1400, "resembling skin," from skin (n.) + -y (2). Meaning "lean, emaciated" is recorded from c. 1600. Of clothes, "tight-fitting" by 1970. In the noun sense of "the truth" it is World War II military slang, perhaps from the notion of the "naked" truth. Related: skinniness.
a child with skinny freckled legs
he wanted the inside skinny on the new partner
skinhead
skink
skinless
skinner
Skinner box
skinny
skinny-dipping
skint
skin-tight
skip
skipjack
