D defs.my
Entry 1 sense Webster, 1913

Indeclinable

· In·de·clin·a·ble · IPA
01 a. Not declinable; not varied by inflective terminations; as, nihil (nothing), in Latin, is an indeclinable noun.
  1. 1.
    Not declinable; not varied by inflective terminations; as, nihil (nothing), in Latin, is an indeclinable noun.(Gram.)