adj.
Pronunciation: th ə t, ' th at
Function: pronoun
Etymology: Middle English, from Old English thæt, neuter relative pronoun, from thæt, neuter demonstrative pronoun
Date: before 12th century
1 ― used as a function word to introduce a restrictive relative clause and to serve as a substitute within that clause for the substantive modified by the clause <the house that Jack built> <I'll make a ghost of him that lets me ― Shakespeare>
2 a : at which : in which : on which : by which : with which : to which <each year that the lectures are given> b : according to what : to the extent of what ― used after a negative <has never been here that I know of>
3 a archaic : that which b obsolete : the person who
usage That, which, who: In current usage that refers to persons or things, which chiefly to things and rarely to subhuman entities, who chiefly to persons and sometimes to animals. The notion that that should not be used to refer to persons is without foundation; such use is entirely standard. Because that has no genitive form or construction, of which or whose must be substituted for it in contexts that call for the genitive.
usage That, which: Although some handbooks say otherwise, that and which are both regularly used to introduce restrictive clauses in edited prose. Which is also used to introduce nonrestrictive clauses. That was formerly used to introduce nonrestrictive clauses; such use is virtually nonexistent in present-day edited prose, though it may occas. be found in poetry.