Old English blis, also bliðs "bliss, merriment, happiness, grace, favor," from Proto-Germanic *blithsjo (source also of Old Saxon blidsea, blizza), from *blithiz "gentle, kind" (see blithe) + *-tjo noun suffix. Originally mostly of earthly happiness, in later Old English of spiritual joy, perfect felicity, the joy of heaven. It has been influenced by unrelated bless.
"attain or exist in a state of perfect felicity," often with out (adv.), by 1973, U.S. colloquial, from bliss (n.).
updated on October 16, 2022