冴寒 （ゴカン） extreme cold

冴える （さえる） to be clear (of a sight, sound, colour, etc.), to be bright, to be vivid, to be crisp, to be clear-headed, to be alert, to be on the ball, to be wide awake, to look upbeat, to be perky, to be cheerful, to master (a skill), to excel at, to cleanly execute, to be satisfying, to become frigid, to become intensely cold