unimpressible

Unimpressible, un-im-pres′i-bl, adj. not capable of being impressed, not readily impressed.

The unimpressible natives stop their paddles as they are floating up an igarape to listen to the dulcet strains.

Mr. Bond's heart is not made of wax, and is a terribly unimpressible object, so far as the ladies are concerned.

Sutton's obduracy had never occurred to her as a serious impediment, yet now he seemed hopelessly unimpressible.

That was probably because they were old men, and unimpressible.