Concise Bible Dictionary:
There are two distinct applications of the word “blessing.” God blesses His people, and His people bless God, the same word being constantly used for both. It is obvious therefore that it must be understood in more senses than one. Again, we read that “the less [or inferior] is blessed of the better” (Heb. 7:7); and though this refers to Melchisedec blessing Abraham, the same thing is true respecting God and His creatures: in bestowing favors God is the only one who can bless. The Christian can say, God “hath blessed us with all spiritual blessings in the heavenlies in Christ” (Eph. 1:3); but the same verse says, “Blessed be the God and Father of our Lord Jesus Christ,” meaning “Thanks be to the God and Father of our Lord Jesus Christ.” This signification is further made clear by the records of the institution of the Lord’s supper. In Matthew and Mark the Lord took bread, and “blessed.” In Luke and in 1 Corinthians 11:24 He took bread and “gave thanks.” “Every good gift and every perfect gift is from above, and cometh down from the Father of lights” (James 1:17). This is God blessing us, and for which we in return bless God by giving thanks, by praise and worship.
From Anstey’s Doctrinal Definitions:
This is mentioned in Scripture in four ways:
Firstly, to denote a state of joy and happiness. The very word "blessed" means happy. For example, Romans 4:7 says, "Blessed are they whose iniquities are forgiven, and whose sins are covered." And Luke 12:37 says, "Blessed are those servants whom the lord when he cometh shall find watching." In this sense, we often pray and ask God to "bless" our time together at some particular event. Thus, we are asking God to give us a happy and spiritually profitable time.
Secondly, the term is used as an ascription of happy thankfulness to God. For example, "I will bless the LORD at all times" (Psa. 34:1). And, "Therewith bless we God, even the Father...." (James 3:9; Eph. 1:3). Hence, we sing, "We bless our Saviour's name, our sins are all forgiven" (Hymn #146 L. F.).
Thirdly, it is used to denote temporal (material) gifts given in the name of the Lord (2 Cor. 9:5-6 – J. N. Darby Trans.).
Fourthly, the term is used to denote our distinctive Christian blessings in Christ. Ephesians 1:3 says, "Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places [the heavenlies] in Christ." These blessings are heavenly, spiritual, and eternal, as opposed to Israel’s, which are earthly, material, and temporal. They are:
• Redemption in Christ Jesus (Rom. 3:24).
• Forgiveness of sins in Christ—a purged conscience (Rom. 4:7; Eph. 4:32; Heb. 9:14).
• Justified in Christ Jesus (Rom. 4:25-5:1; Gal. 2:16-17).
• The gift of the Spirit in Christ—anointed, sealed, and given the earnest of the Spirit (Rom. 5:5; 2 Cor. 1:21-22; Eph. 1:13).
• Reconciliation in Christ Jesus—“made nigh” (Rom. 5:10; Eph. 2:13; Col. 1:21).
• Sanctified in Christ Jesus (Rom. 6:19; 1 Cor. 1:2).
• Eternal Life in Christ Jesus (Rom. 6:23; 2 Tim. 1:1).
• Deliverance (Salvation) in Christ Jesus (Rom. 8:1-2).
• Sonship in Christ Jesus (Rom. 8:14-15; Gal. 3:26; 4:5-7).
• Heirship of the inheritance in Christ (Rom. 8:17; Eph. 1:10-11; Gal. 3:29).
• New creation in Christ Jesus (Rom. 8:29; Gal. 6:15; 2 Cor. 5:17).
• One body in Christ (Rom. 12:5).
(Note: the above Scripture references are from the J. N. Darby Translation.)