from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Without grammatical inflection.
- adj. Of or being a word that lacks grammatical inflection though belonging to a form class whose members are usually inflected.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. not grammatically inflected, especially if others of its class are usually inflected
- n. A word that is not grammatically inflected.
from the GNU version of the Collaborative International Dictionary of English
- adj. Not declinable; not varied by inflective terminations.
from The Century Dictionary and Cyclopedia
- In grammar, not declinable; not varied by declension; showing no variety of form for case, number, or the like.
- n. In grammar, a word that is not declined.
Latin indeclinabilis: compare French indéclinable. See in- not, and decline. (Wiktionary)