Definitions
American Heritage® Dictionary of the English Language, Fourth 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.
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.
Wiktionary
- adj. grammar, of a word not grammatically inflected, especially if others of its class are usually inflected
- n. grammar A word that is not grammatically inflected.
GNU Webster's 1913
- adj. (Gram.) Not declinable; not varied by inflective terminations.
Etymologies
- Latin indeclinabilis: compare French indéclinable. See in- not, and decline. (Wiktionary)
Examples
“A statement was put forward on Vicipaedia for gas, indeclinable, as the Latin term, because the located scientific usages of the term in Latin texts (from 1652, which even gives the etymology) are just that.”
The Vatican’s Dictionary of Recent Latinity « The Half-Baked Maker
“By 1794, writers of scientific Latin, perhaps fed up with the non-Latin sound of gas as an indeclinable, had changed to gas, - is, a noun of the third declension.”
The Vatican’s Dictionary of Recent Latinity « The Half-Baked Maker
“In politics, reform is an indeclinable and urgent task to bring about changes in legislation so that our young democracy can move forward, strengthen the direction taken by political parties and fine-tune our institutions, restoring values and providing more transparency in all types of public activity.”
“Actually, Jesus is indeclinable, so the plural would be Jesus.”
Neanderthal/human interbreeding - the old-earth response - The Panda's Thumb
“Hillbilly, the word for seven in Latin, septem, is indeclinable, so you can't use sevi to say multiple sevens.”
“In the second line saraddham is not an indeclinable; or, if it be taken as such, the sense may still remain unaltered.”
The Mahabharata of Krishna-Dwaipayana Vyasa, Volume 3 Books 8, 9, 10, 11 and 12
“The adjective is here put in the ablative, to denote the place where, and in the neuter gender, _humi_ being regarded as indeclinable.”
“Mīlle is regularly an adjective in the Singular, and indeclinable.”
“A very few indeclinable adjectives occur, the chief of which are frūgī,”
“In the records of the trullan Council (692) we meet the name of Marianus, Bishop of Kitharizon (or Kithariza), for the name seems to have been indeclinable (Lequien, I, 453).”
Lists
These user-created lists contain the word ‘indeclinable’.
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Word Words
This used to be my nym list, but there are so many words about words, I think it's time to expand and open.
acronym, antonym, aptronym, autoantonym, autonym, bacronym, capitonym, contranym, contronym, eponym, exonym, heteronym and 120 more...
Tweets
Looking for tweets for indeclinable.

Derek Fok The current definitions and examples for indeclinable do not really help me to use or understand the word. I had to google it to find a better example.
It seems relegated to grammatical jargon, since undeclinable better captures the description of things other than words that may not be declined.
It seems that the grammarians and linguists have taken ownership of declinable and indeclinable. The definitions in Wordnik for declinable does not even capture the meaning that is given in the example. To correct this should be an undeclinable challenge. Mar 4, 2010