(noun) the language or speech pattern of one individual at a particular period of life
the real "problem" of the text is the way in which the narrator adopts and/or simulates the protagonist's subjective stance and idiolect.
on The Depressed Person
scratching away at his notebook in his idiolectic hieroglyphics
Twenty-first-century Marxists must be nimble if we are to revive our own idiolect
notwithstanding his particular idiolect