unaccustomed

yllättävä, tavaton

tottumaton Not used to an event or thing, not accustomed.
(RQ:Fielding Tom Jone)

I again conveyed his key into his pocket, and counterfeiting sleep—though I never once closed my eyes, lay in bed till after he arose and went to prayers—an exercise to which I had long been unaccustomed.

He is unaccustomed to the cold.