who's

Etymology 1
Contractions; +.

Contraction

 * 1) Who is.
 * 2) Who has.
 * 3)  Whom is.
 * 4)  Who (whom) does
 * 1)  Whom is.
 * 2)  Who (whom) does
 * 1)  Who (whom) does

Etymology 2
From.