oillet
/ˈɔɪlɪt/(also oilet) Now archaic and historical
noun
An aperture or loophole for observation, especially in a wall; = eyelet. Now ( Architecture ): a round opening at the end of an arrow-slit ( historical ).
Origin
Middle English. From Anglo-Norman oillet, ollet little eye and Middle French oeuillet, oillet, oeillet (French oeillet) small round hole in fabric, little eye, window surround in form of an eye, small eye of a plant from Anglo-Norman oil, Middle French oeïl eye + -et.