窄(zhǎi) - narrow in Mandarin

窄 (zhǎi) means "narrow", describing anything short on width: a road, a doorway, a pair of sleeves, a gap between two buildings. It sits as an ordinary stative adjective in Mandarin, needing no separate verb "to be": 这条路很窄 (zhè tiáo lù hěn zhǎi), "this road is very narrow", with 很 (hěn) doing duty as a mild intensifier rather than "very" in the English sense.

Its natural opposite is 宽 (kuān, "wide, broad"), and the pair 宽窄 (kuān zhǎi) together can mean "width" as an abstract noun, the same trick English uses when it turns "wide" and "narrow" into a single measurable quality.

Be careful not to reach for 窄 (zhǎi) when you mean cramped or tight in a general sense - 挤 (jǐ, "crowded, squeezed") is the better word for a packed room or a crowded bus. 窄 (zhǎi) is specifically about width, not lack of space overall.