不忙 (bù máng) literally means 'not busy' — it combines the negation particle 不 (bù) with the adjective 忙 (máng), meaning 'busy'. As a two-character phrase, it functions primarily as an adjective describing a person's current state of having free time or low workload. It is commonly used in casual conversation to indicate availability, often in response to questions about schedule or willingness to help.

This phrase is neutral in register and appears frequently in everyday spoken Chinese — for example, when declining an invitation politely ('I’m not busy right now') or offering assistance ('Are you busy? No, I’m not busy'). Unlike some adjectives that require 很 or other degree words before them, 不忙 can stand alone as a complete predicate without modification. It’s also frequently paired with time markers like 现在 (now) or 今天 (today) to specify context.