We cannot determine the denotation or connotation of psalms, hymns and Spiritual songs by any modern usage of these same words. The meaning and reference must be determined by the usage of Scripture. The use of these terms psalm, hymn, song in the Greek Septuagint Version, current in the apostolic church, is not to be ignored. There is no doubt that these terms were the familiar designations for various selections in the Psalter. There is not use of these terms in the New Testament where it can be shown that they designate other than inspired compositions.
Most references are clearly to the book of Psalms.
But then the question arises whether this word qualifies only the songs, or all three of the designated types of praise. Professor Murray argues that the former is the more natural interpretation. But even if we opt for the latter, he insists that the conclusion will be the same. For a Psalm, by Scriptural usage, is an inspired composition. And by this interpretation so must a song be.