frost·y (frô st, fr s t) adj. frost·i·er, frost·i·est. 1. Producing or characterized by frost; freezing. See Synonyms at cold. 2. Covered with or as if with frost.
adjective frostier frost′i·er, frostiest frost′i·est. producing frost or cold enough to produce frost; freezing; covered with or as with frost; hoary, glistening, etc.