An Etymological Dictionary of Astronomy and Astrophysics

A usually metal instrument used to operate a lock’s mechanism.

Etymology (EN): M.E. key(e), kay(e), O.E. cæg “key,” of unknown origin,

Etymology (PE): Kelid, variants (Tabari) kali, (Lori) kelil, (Laki) kalil “key; lock,” (Kurd) kilil, kolun “latch, bolt;” Mid.Pers. kilêl “key.” See also → include.