Added 9 October 2026 phanerozoic noun Categories: TimeRare Words noun ! Definition from WordNet 3.1, Princeton University. More about phanerozoic at Wordnik → Where our words come from → The period from about 540 million years ago until the present, a period when abundant life existed. Related Words: eonironstonesophiolitesphanaerozoicpaleozoicproterozoicpalaeozoicpalæozoicmesozoicarchaeozoicecozoicprecambrian Back to today's word