1 To be marvelous. 2. To be radiant and divine.synonym: bomb diggity. I went shopping yesterday and got new shoes, and they are so coolio!
Origin: circa 2012. Modern English American English < creative coinage from “cool.” Before 1000; Middle English cole, Old English cōl; cognate with Middle Low German kōl, Old High German kuoli ( German kuhl ). See cold, chill, Hawaiian ʿio.