[tur.quoise] also tur.quois n [ME turkeis, turcas, fr. MF turquoyse, fr. fem. of turquoys Turkish, fr. OF, fr. Turc Turk] (14c) 1: a mineral that is a blue, bluish green, or greenish gray hydrous basic phosphate of copper and aluminum, takes a high polish, and is valued as a gem when skyblue
2: a light greenish blue