A blessing, praise, or generous gift. The noun form encompasses both the act of blessing (praise directed to God) and the content of blessing (good things received from God). It also means 'bounty' or 'generous gift,' as in 2 Corinthians 9:5 where a collection is called a eulogia — a blessing-gift.
Eulogia captures the circularity of blessing in God's economy. God blesses us; we bless Him with praise; we become blessings to others. In Galatians 3:14, the 'blessing of Abraham' comes to the Gentiles through Christ — the promise that all nations would be blessed through Abraham's offspring. Blessing is never meant to terminate on the recipient; it flows through us to the world.