A blessing (from to bless, Old English bleodsian or bletsian) originally meant "sprinkling with blood" during the pagan sacrifices, the Blóts (reference: AHD).
A blessing, (also used to refer to bestowing of such) is the infusion of something with holiness, divine will, or one's hopes. Within Roman Catholicism, Eastern Orthodoxy, and similar traditions, formal blessings of the church are performed by bishops, priests, and sometimes deacons, but as in many other religions, anyone may formally bless another. A curse at least in its most formal sense is the opposite of a blessing. Blessing is similar to charm.
In the Bible, blessings and curses are related; the book of Deuteronomy prescribes that obedience to the Torah brings God's blessing, while disobedience brings a curse. The Priestly Blessing is set forth at Numbers 6:24-26:
May the LORD bless you, and keep thee;
May the LORD make his face shine to upon you, and be gracious to you;
May the LORD turn his countenance to you and grant you peace.
This formula has been introduced into Roman Catholic worship as well. In the Gospel of Matthew, Jesus pronounces blessings on the poor, the humble, and the persecuted in the Beatitudes at the beginning of the Sermon on the Mount.
Printed with permission from Catholic Expert.