theirs
UK /ðɛəz/ · US /ðɛɚz/ pronoun
Also a form of they
Forms their's
- pronoun That or those belonging to them; the possessive case of they, used without a following noun. “This luggage is theirs. These passports are also theirs.”
- pronoun (informal) Their house or home. “Let's go over to theirs.”
Etymology
From Middle English theires, attested since the 1300s. Equivalent to their + -s (compare -'s); formed by analogy to his. Displaced theirn (from Middle English theiren, formed by analogy to mine, thine) in standard speech.
Sources: Wiktionary — from the Wiktionary entry “theirs”, CC BY-SA 4.0. Details