Li"as (?), n. [Cf. F. lias, fr. liais sort of limestone, OF. also liois; perh. of Celtic origin, cf. Armor. liach, leach, a stone, Gael. leac, W. llech. Cf. Cromlech.] Geol.
The lowest of the three divisions of the Jurassic period; a name given in England and Europe to a series of marine limestones underlying the Oolite. See the Chart of Geology.
© Webster 1913.