An example of whom is someone asking which person someone is speaking to, "To whom are you speaking?"
Origin of whomMiddle English from Old English hwam, dative of hwa, who
Origin of whomMiddle English from Old English hwǣm, hwām ; see kwo- in Indo-European roots.
(the singular and plural objective case of who)
- (formal) What person or people; which person or people, as the object of a verb.
- Whom did you ask?
- (formal) What person or people; which person or people, as the object of a preposition.
- To whom are you referring? With whom were you talking?
- Him; her; them (used as a relative pronoun to refer to a previously mentioned person or people.)
- He's a person with whom I work.; We have ten employees, half of whom are carpenters.
whom is only used as an object, whereas who is always used where a subject is required. In other words, whom may be thought of as being similar to us, them, etc, whereas who may be thought of as being similar to we, they, etc.
However, in both spoken and most written language, who is also often used as an object in place of whom. This makes who similar to you and it which also use the same form for subjects and objects.
Some prescriptivists regard such usage as incorrect, and insist on using whom to maintain a distinction between subjects and objects. This makes the distinction between who and whom comparable to the distinction between we and us, or between they and them.
To some speakers (especially in US English), the use of whom is characteristic of a formal style. To some of these speakers, whom may sound stilted in informal conversation. Whom is more common in UK English, particularly after a preposition (with whom, from whom, etc).
Subject (always who):
Old English hwam