from the GNU version of the Collaborative International Dictionary of English
- n. The quality of being abstruse; difficulty of apprehension.
from The Century Dictionary and Cyclopedia
- n. The state or quality of being abstruse, or difficult to be understood; difficulty of apprehension.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the quality of being unclear or abstruse and hard to understand
- n. wisdom that is recondite and abstruse and profound
abstruse + -ness (Wiktionary)