c. 1300, covenaunt, "mutual compact to do or not do something, a contract," from Old French covenant, convenant "agreement, pact, promise" (12c.), originally present participle of covenir "agree, meet," from Latin convenire "come together, unite; be suitable, agree," from com- "together" (see com-) + venire "to come," from a suffixed form of PIE root *gwa- "to go, come."
In law, "a promise made by deed" (late 14c.). Applied in Scripture to God's arrangements with man as a translation of Latin testamentum, Greek diatheke, both rendering Hebrew berith (though testament also is used for the same word in different places). Meaning "solemn agreement between members of a church" is from 1630s; specifically those of the Scottish Presbyterians in 1638 and 1643 (see covenanter).