- Geology. the third stage of the glaciation of North America during the Pleistocene.
- Geology. of or relating to the Illinoian stage.
Origin of Illinoian
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for illinoian
Specific identification of the Illinoian pocket gophers is uncertain, primarily due to the fragmentary nature of the material.
The ancient channel which it held along the Illinoian ice front has been traced through southeastern Iowa for many miles.The Elements of Geology
William Harmon Norton