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" 同義詞:glacial period, glacial epoch,
百科解釋
An ice age, or more precisely, a glacial age, is a period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers. Within a long-term ice age, individual pulses of cold climate are termed "glacial periods" (or alternatively "glacials" or "glaciations" or colloquially as "ice age"), and intermittent warm periods are called "interglacials".