签字
qiān zì · HSK 5
to sign
✍️ 签字 = 签 (sign/label) + 字 (character) — sign characters
签 originally meant a bamboo slip or label used for marking; paired with 字 (written character), the compound literally reads as putting your characters on a label, i.e. signing your name.
签 — bamboo radical 竹 (⺮) + 佥 (qiān, phonetic)
Originally written 籤, this character depicts bamboo strips (⺮) used as markers, tags, or lots drawn for divination. The component 佥 supplies the sound. Over time the meaning broadened from physical bamboo slips to labels, signatures, and signing one's name.
字 — roof 宀 + child 子
Originally depicted a child 子 under a roof 宀, suggesting birth or rearing a child in the home. The meaning later extended to 'to give birth, nurture' and then to 'written character', since characters were seen as offspring derived from earlier pictographs.