who

from The Century Dictionary.

• Denoting a personal object of inquiry: What man or woman? what person?
• In certain special uses who appears
• Inquiring as to the character, origin, or status of a person: as, who is this man? (that is, what are his antecedents, his social standing, etc.); who are we (what sort of persons are we) that we should condemn him?
• In exclamatory sentences, interrogative in form but expecting or admitting no reply: as, who would ever have suspected it!
• Introducing a dependent clause, and noting as antecedent a subject, object, or other factor, expressed or understood, in a clause actually or logically preceding.
• The antecedent is sometimes omitted, being implied in the pronoun, which is in this case usually called a compound relative.
• A clause dependent in form, but adding a distinct idea. Here the relative force is almost entirely lost, who becoming equivalent to and with a demonstrative pronoun.
• With reference to gender, who originally noted a masculine or feminine antecedent, whether human, animate, or other, the neuter being what; and whose, the possessive (genitive)of who, was also that of what, and is still correctly used of a neuter antecedent (see what). Moreover, before the appearance of the possessive its, whose place was filled by the neuter his (see he, I., C. ), not only were neuter objects designated in the two other cases by he and him, but who and whom were sometimes substituted for that as the nominative and objective of the neuter relative (see the quotation from Puttenham). In modern use, however, who and whom are applied regularly to persons, frequently to animals, and sometimes even to inanimate things when represented with some of the attributes of humanity, as in personification or vivid description.
• With reference to the nature of its antecedent, who may note
• a particular or determinate person or thing (see ); or
• an indefinite antecedent, in which case who has the force of whoso, whosoever, or whoever, and is called an indefinite relative. Its antecedent may be expressed, or it may be a compound relative.
• Synonyms Who, which, and that agree in being relatives, and are more or less interchangeable as such; but who is used chiefly of persons (though also often of the higher animals), which almost only of animals and things (in old English also of persons), and that indifferently of either, except after a preposition, where only who or which can stand. Some recent authorities teach that only that should be used when the relative clause is limiting or defining: as, the man that runs fastest wins the race; but who or which when it is descriptive or coördinating: as, this man, who ran fastest, won the race; but, though present usage is perhaps tending in the direction of such a distinction, it neither has been nor is a rule of English speech, nor is it likely to become one, especially on account of the impossibility of setting that after a preposition; for to turn all relative clauses into the form “the house that Jack lived in” (instead of “the house in which Jack lived”) would be intolerable. In good punctuation the defining relative is distinguished (as in the examples above), by never taking a comma before it, whether it be who or which or that. Wherever that could be properly used, but only there, the relative may be, and very often is, omitted altogether: thus, the house Jack built or lived in; the man (or the purpose) he built it for. The adjective clause introduced by a relative may qualify a noun in any way in which an adjective or adjective phrase, either attributive or appositional can qualify it, and has sometimes a pregnant implication of one or another kind: as, why punish this man, who is innocent? i. e. seeing, or although, he is innocent (= this innocent man). But a relative is also not rarely made use of to add a coördinate statement, being equivalent to and with a following pronoun: as, I studied geometry, which I found difficult (and [I] found it difficult); I met a friend, who kindly showed me the way (and he kindly, etc.). This way of employing the relative is by some regarded as a Latinism, and condemned; it is restricted to who and which.

from the GNU version of the Collaborative International Dictionary of English.

• pronoun 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.
• pronoun Obs., except in the archaic phrase, as who should say. One; any; one.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• pronoun interrogative pronoun What person or people; which person or people (used in a direct or indirect question).
• pronoun relative pronoun The person or people that.
• noun A person under discussion; a question of which person.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

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