'条子' (tiáozi) is a colloquial noun meaning 'note' or 'slip of paper' — typically a small, handwritten or printed piece of paper used for quick communication. The character 条 (tiáo) originally means 'strip' or 'long narrow object', and 子 (zi) is a common diminutive or nominal suffix. Together, they evoke the physical shape and informal nature of a note — thin, portable, and temporary. It's widely used in everyday spoken Mandarin, especially in workplaces, schools, or casual settings where people leave reminders, instructions, or short messages.

This term carries a relaxed, slightly informal register — it would sound odd in formal documents or official announcements. You’ll often hear it in phrases like '写个条子' (write a note) or '留张条子' (leave a note). While not slang per se, it’s noticeably more casual than the standard word '便条' (biàntiáo), and rarely appears in formal writing or news reports.