I. krə̇ˈtāshəs adjective
Etymology: Latin cretaceus, from creta chalk
1. : relating to, having the characteristics of, or abounding in chalk : chalky
cretaceous formations
2. usually capitalized : of or relating to the last period of the Mesozoic era and the corresponding system of rocks, the deposits of the period including the larger part of the known chalk beds, greensand marl, and most of the coal of the United States west of the Great Plains, the vegetation of the period having approached the modern temperate and subtropical flora in general aspect, and the reptiles of the period having remained dominant on the land and in the sea, ganoid fishes for the first time having become subordinate to teleosts — see geologic time table
• cre·ta·ceous·ly adverb
II. noun
( -es )
Usage: usually capitalized
: the Cretaceous period or system of rocks