phanerozoic eon is a noun meaning "the period from about 540 million years ago until the present, a period when abundant life existed". It carries one recorded sense.
the period from about 540 million years ago until the present, a period when abundant life existed
Definitions, synonyms and semantic relations for phanerozoic eon come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.