possessive pronoun

theirs

theirs

This book is theirs.

This book is theirs.

Our house is big, but theirs is small.

Our house is big, but theirs is small.

((sth.)) is theirs The responsibility is theirs.

Synonyms: their own; Antonyms: ours, yours, his, hers

From Old English *þeira*, genitive of *þeir* ('they'). The '-s' ending developed in the 14th century, similar to 'his' or 'yours'.

It's 'their' + 's'. Remember it never has an apostrophe. 'It's theirs,' not 'It's their's.'

This page is designed for learning support. Please use it as a learning reference, not as a formal reference.