‘窄缝’ literally combines 窄 (zhǎi), meaning 'narrow' or 'tight', and 缝 (fèng), meaning 'crack', 'slit', or 'gap'. Together, they form a compound noun describing a very thin, elongated opening—typically one that is naturally occurring or unintentionally formed, such as in rock formations, tree bark, or animal burrows. It emphasizes both the narrowness and the linear, often irregular shape of the opening.

This word is commonly used in descriptive or observational contexts—especially in nature writing, field biology, or storytelling—to evoke tight, hidden, or hard-to-access spaces. It carries a neutral-to-slightly-concrete tone and is more literary or precise than general terms like ‘缝隙’ (xìfèng). You’ll often encounter it when describing how small animals move through confined spaces or how light filters through tight openings.