[intransitive, transitive] to write your name on a document, letter, etc. to show that you have written it, that you agree with what it says, or that it is genuine Sign here, please. sign something Sign your name here, please. You haven't signed the letter. to sign a cheque The treaty was signed on 24 March. The player was signing autographs for a group of fans. sign yourself + noun He signed himself ‘Jimmy’.