- A narrow opening, often cruciform, through which arrows may be fired.
- A narrow orifice, often cruciform, whereby arrows could be released.
- In old fortification: A loophole or aperture within the wall surface of a fortification, or in a wooden hoarding temporarily post for defense, through which crossbowmen might discharge their bolts. See loophole, and compare archeria.
- A room in which balisters or crossbows were kept.