I. noun
also ly·as ˈlīəs
( -es )
Usage: often attributive
Etymology: Middle English lyas, from Middle French liois, probably from lie dregs; from the appearance — more at lee
: a kind of blue limestone found especially in southwestern England
II. adjective
Usage: usually capitalized
Etymology: from Lias oldest division of the European Jurassic system, from lias (I)
: of or relating to a subdivision of the European Jurassic — see geologic time table