theirs

alternative obsolete their's

1. That or those belonging to them; the possessive case of they, used without a following noun.

   Theirs cost a lot more than ours.

   3 more examples

   This luggage is theirs. These passports are also theirs.

   That cat of theirs got into our garden again.

   The letter had been given to the two Englishmen by a good friend of theirs in London, who had been in America two years previously, and had singled out Mr. J. L. Westgate from the many friends he had left there as the consignee, as it were, of his compatriots.

   1878, Henry James, An International Episode

2. informalTheir house or home.

   Let's go over to theirs.