noun
A narrow vertical opening in a castle wall or fortification for shooting arrows. The term is specific to Japanese castle architecture.
城の石垣には矢狭間がいくつも設けられていた。
The castle's stone walls had many arrow-slits.
鉄砲狭間 is a similar opening designed for firearms rather than arrows.
Compound of 矢 (ya, 'arrow') and 狭間 (hazama, 'gap, opening'), with rendaku voicing of hazama to -zama.