Easton's Bible Dictionary

Hymn - occurs only Eph. 5:19 and Col. 3:16. The verb to "sing an hymn" occurs Matt. 26:30 and Mark 14:26. The same Greek word is rendered to "sing praises" Acts 16:25 (R.V., "sing hymns") and Heb. 2:12. The "hymn" which our Lord sang with his disciples at the last Supper is generally supposed to have been the latter part of the Hallel, comprehending Ps. 113-118. It was thus a name given to a number of psalms taken together and forming a devotional exercise.

The noun hymn is used only with reference to the services of the Greeks, and was distinguished from the psalm. The Greek tunes required Greek hymns. Our information regarding the hymnology of the early Christians is very limited.