from The American Heritage® Dictionary of the English Language, 4th Edition
- transitive v. To make or become tough. See Synonyms at harden.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To make tough.
- v. To become tough.
from the GNU version of the Collaborative International Dictionary of English
- v. To grow or make tough, or tougher.
from The Century Dictionary and Cyclopedia
- Specifically, of copper, in its metallurgy, the elimination of the foreign metals as oxids and of copper oxid itself, changing the qualities of the cast from brittleness to ductility.
- To grow tough or tougher.
- To make tough or tougher.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- v. make tough or tougher
Sorry, no etymologies found.