Meaning

verb give a benediction to

verb confer prosperity or happiness on

verb make the sign of the cross over someone in order to call on God for protection; consecrate

originFrom Middle English blessen, from Old English bletsian (“to consecrate (with blood)”), from Proto-West Germanic *blōdisōn (“to sprinkle, mark or hallow with blood”), from Proto-Germanic *blōþą (“blood”), of uncertain origin, possibly from Proto-Indo-European *bʰleh₃- (“to bloom”). Cognate with Old Norse bleza (“to bless”) (whence Icelandic blessa), Old English blēdan (“to bleed”). More at bleed.

Etymology from Wiktionary, CC BY-SA 3.0