Hebrew barak (verb), berakah (noun); Greek eulogeō, eulogia — from which "eulogy." In Scripture, blessing has two related senses: (1) God's bestowal of favor, flourishing, and covenantal goodness upon His people (material and spiritual); (2) human invocation of God's favor upon another (a father upon His son, a priest upon the people, one believer upon another). The biblical picture of blessing runs from Genesis 1:28 ("God blessed them") through Numbers 6:24-26 (the Aaronic blessing) to Ephesians 1:3 ("Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing") to the final benediction of Revelation.
Blessing is one of the richest biblical categories and one modern Christians routinely miss. Four observations. (1) Blessing flows from God and returns to Him. God blesses us with covenantal goodness; we bless Him with praise, obedience, worship. The two directions share the same vocabulary because they share the same logic — God is the source, sustainer, and goal of all flourishing. (2) The Aaronic blessing. "The LORD bless you and keep you; the LORD make his face to shine upon you and be gracious to you; the LORD lift up his countenance upon you and give you peace" (Numbers 6:24-26) — the central OT blessing formula, pronounced by the priests over Israel. Its structure is a three-fold invocation of the Name; God explicitly says "they shall put my name upon the people of Israel, and I will bless them" (6:27). (3) Fathers bless their children. Jacob blessed his sons with specificity (Genesis 49); Isaac blessed Jacob (Genesis 27, with messianic weight transmitted). The role of the father in pronouncing blessing over his children is a recovered practice many Christian fathers today have never experienced and cannot therefore give. Learn it. Pronounce blessing aloud on your children and grandchildren. (4) Every spiritual blessing. Ephesians 1:3 is the New Covenant summary: every spiritual blessing is already yours in Christ — chosen before creation, adopted, redeemed, forgiven, sealed with the Spirit, guaranteed inheritance. The Christian lives out of an inheritance already given, not a blessing he is still trying to earn.