radiation

1. The shooting forth of anything from a point or surface, like diverging rays of light.Examples: "heat radiation"Synonyms: EMRabbreviationalt-ofcountableellipsisoftenuncountable

2. (evolutionary theory, countable) A rapid diversification of an ancestral species into many new forms.Examples: "So the question is: have plants and animals retained over this huge amount of time—whole radiations of mammals have come and gone in this period—have they retained these potentially costly characteristics?"; "The second [canid group] is the radiation of dogs in South America that began when the first canids arrived about 3 Ma, after crossing the Panama land bridge (Fig. 5.4)."countable