(demonstrative) The thing, person, idea, quality, event, action or time indicated or understood from context, especially if more remote geographically, temporally or mentally than one designated as "this", or if expressing distinction.
The known (thing); used to refer to something just said.
(demonstrative) The aforementioned quality or proposition; used to emphatically affirm or deny a previous statement or question.
(relative) (plural that) Which, who; representing a subject, direct object, indirect object, or object of a preposition.
Used in place of relative adverbs such as where or when; often omitted.