签字 (qiān zì) is a verb meaning 'to sign one’s name'—typically on documents, forms, contracts, or receipts. The first character 签 (qiān) means 'to sign' or 'to endorse', often used in formal or official contexts; the second character 字 (zì) means 'character' or 'name', and together they literally mean 'sign one’s name'. This term emphasizes the act of writing one’s full name as a mark of agreement, authorization, or identity verification.

It’s commonly used in administrative, legal, educational, and business settings—for example, signing enrollment forms, delivery confirmations, or consent letters. Unlike the more general verb 签 (qiān) alone—which can mean 'to sign' or 'to sign up'—签字 specifically refers to the physical or digital act of writing one’s name. It’s neutral in register but implies formality and intentionality; it’s rarely used for casual autographs (where 签名 is preferred).