The announcement of a temporal loss or of eternal loss as a punishment for sin made by God Himself or by one speaking in the name of God; as in Genesis 3, and Deuteronomy 11.
It may mean also the wishing of evil to a person from a sentiment of hatred or the like, against that person, or from a natural resentment on account of some offense deserving punishment.
It was a widespread belief in antiquity that malediction no less than benediction was efficacious of itself, when uttered by one in authority (Numbers 22; Genesis 9:27).
For a son to utter a malediction against his parents was a crime punishable with death (Exodus 21; Leviticus 20; Proverbs 20; 30).
New Catholic Dictionary