from The American Heritage® Dictionary of the English Language, 4th Edition
- transitive v. To make or become steep or steeper.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To make steeper.
- v. To become steeper.
from the GNU version of the Collaborative International Dictionary of English
- intransitive v. To become steep or steeper.
from The Century Dictionary and Cyclopedia
- To become steep.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- v. become steeper
- v. make steeper
steep + -en (Wiktionary)