Hymns are indeed songs of praise to God. Still, a dictionary definition can't begin to grasp the riches of the Church's hymns. For example, some hymns are not so much praise to God as they are prayer.
Hymns can be confessions of sin or confessions of faith.
Some hymns give praise to God by telling the story of what He has done. Finally, there are many hymns that masterfully teach the Christian faith, even as they lead God's people to praise their Maker and Redeemer. Before celebrating Jesus' birth, Christians do well to prepare their hearts for His coming. Rejoice, then, you sad-hearted, Who sit in deepest gloom. We have much in common with ancient Israel, for we often find ourselves overshadowed by the darkness of sin and the trials of life.