from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Of or relating to a lichen whose thallus is thin, crusty, and closely adherent to or embedded in the surface on which it grows.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of a lichen, growing tightly appressed to the substrate.
from The Century Dictionary and Cyclopedia
- Crust-like; crustaceous.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. (of lichens) having a thin crusty thallus that adheres closely to the surface on which it is growing
Latin crūstōsus, crusted, from crūsta, crust; see kreus- in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin crustōsus ("with a hard crust"). (Wiktionary)