THEIRS theirs (no apostrophe) This is my dog; THEIRS has a white patch on his forehead. theirselves Incorrect formation. See THEMSELVES. themselves They blame THEMSELVES for the crash. They THEMSELVES were there. there See THEIR, THERE OR THEY'RE?. there is/there are See SINGULAR OR PLURAL? (iii). thesis (singular) theses (plural) See FOREIGN PLURALS. they're See THEIR, THERE OR THEY'RE?. thief (singular) thieves (plural) See PLURALS (v). thorough thoroughly thorough + ly threshold (not -hh-) ti