Noun

• S: (n) ice age, glacial period, glacial epoch (any period of time during which glaciers covered a large part of the earth's surface) "the most recent ice age was during the Pleistocene"
• direct hypernym / inherited hypernym / sister term
• S: (n) period, geological period (a unit of geological time during which a system of rocks formed) "ganoid fishes swarmed during the earlier geological periods"
• part holonym
• S: (n) prehistory, prehistoric culture (the time during the development of human culture before the appearance of the written word)