possess. det.
- belonging to or associated with the people or things previously mentioned or easily identified.
- belonging to or associated with a person of unspecified sex (used in place of either ‘his’ or ‘his or her’).
-
(Their)
used in titles.
Usage
Do not confuse their and there. Their means ‘belonging to them’ (I went to their house) while there means ‘in, at, or to that place’ (it took an hour to get there).
On the use of their in the singular to mean ‘his or her’, see usage at they.
Etymology
ME: from ON their(r)a ‘of them’, genitive pl. of the demonstrative sá; rel. to them and they.