indeclinable

/ˌɪndɪˈklaɪnəbəl/
adjective
  1. (of a word, especially in grammar) not changing its form to show grammatical case, number, or gender.
    • Students often struggle with indeclinable adjectives in German because they never add endings.
    • The word 'sheep' is indeclinable in English, staying the same in both singular and plural.
    • In Latin, most nouns are declinable, but some like 'cornu' are indeclinable.
What does "indeclinable" mean? | whatsthatwordmean | whatsthatwordmean