不宜 is an adjective meaning 'not advisable' or 'unsuitable', commonly used to warn against certain actions, foods, environments, or conditions—especially in health, medicine, and daily life contexts. The character 不 means 'not', while 宜 means 'suitable', 'appropriate', or 'advisable'; together, they form a concise, formal expression of caution or prohibition. It often appears in written instructions, medical advice, weather reports, or dietary guidelines.

This term carries a neutral-to-formal register and is rarely used in casual spoken Chinese; native speakers tend to use simpler alternatives like 不好 (bù hǎo) or 最好别 (zuì hǎo bié) in conversation. 不宜 is frequently followed by a verb (e.g., 不宜食用, 不宜剧烈运动) or a noun phrase (e.g., 不宜人群), indicating who or what the warning applies to. It implies objective unsuitability based on reason, evidence, or convention—not personal preference.