slang for "female pudenda," 1879, but probably older; perhaps from Old Norse puss "pocket, pouch" (compare Low German puse "vulva"), but perhaps instead from the cat word (see pussy (n.1)) on notion of "soft, warm, furry thing;" compare French le chat, which also has a double meaning, feline and genital. Earlier uses are difficult to distinguish from pussy (n.1), as in:
The word pussie is now used of a woman [Philip Stubbes, "The Anatomie of Abuses," 1583]
But the absence of pussy in Grose and other early slang works argues against the vaginal sense being generally known before late 19c., as does its frequent use as a term of endearment in mainstream literature, as in:
"What do you think, pussy?" said her father to Eva. [Harriet Beecher Stowe, "Uncle Tom's Cabin," 1852]
Pussy-whipped first attested 1956 (Middle English had cunt-beaten "impotent," in reference to a man, mid-15c.).