Origin of theirsMiddle English theires from theyr (see their) + -es by analogy with his, his
pron.used with a sing. or pl. verb
- Used to indicate the one or ones belonging to them: The red house is theirs. If your car doesn't start, take theirs.
- Usage Problem His or hers: brought his own lunch and expected everybody else to bring theirs. See Usage Note at he1. See Usage Note at they.
Origin of theirsMiddle English from their their ; see their .
their +"Ž -'s