n. A female castellan; the lady of the castle or château. See chatelain.n. A chain, or group of chains, worn by castellans, by which the keys of a castle were suspended from the girdle; hence, a similar modern device for suspending watch-keys, seals, trinkets, etc.; and so, by extension, the trinkets themselves.Pertaining to or of the nature of a chatelaine: as, a chatelaine watch.