Who
object.
Originally, an interrogative pronoun, later, a relative
pronoun also; -- used always substantively, and either as singular or
plural. See the Note under What, pron., 1. As interrogative pronouns,
who and whom ask the question: What or which person or persons? Who and
whom, as relative pronouns (in the sense of that), are properly used of
persons (corresponding to which, as applied to things), but are
sometimes, less properly and now rarely, used of animals, plants, etc.
Who and whom, as compound relatives, are also used especially of
persons, meaning the person that; the persons that; the one that;
whosoever.