From BiblePortal Wikipedia

Vine's Expository Dictionary of NT Words [1]

1: Ψαλμός (Strong'S #5568 — Noun Masculine — psalmos — psal-mos' )

primarily denoted "a striking or twitching with the fingers (on musical strings);" then, "a sacred song, sung to musical accompaniment, a psalm." It is used (a) of the OT book of "Psalms,"  Luke 20:42;  24:44;  Acts 1:20; (b) of a particlular "psalm,"  Acts 13:33 (cp. ver. 35); (c) of "psalms" in general,   1—Corinthians 14:26;  Ephesians 5:19;  Colossians 3:16 .

 James 5:13MelodySing.

King James Dictionary [2]

PSALM, n. s`am. L. psalmus Gr. to touch or beat, to sing.

A sacred song or hymn a song composed on a divine subject and in praise of God. The most remarkable psalms are those composed by David and other Jewish saints, a collection of one hundred and fifty of which constitutes a canonical book of the Old Testament, called Psalms, or the book of Psalms. The word is also applied to sacred songs composed by modern poets, being versifications of the scriptural psalms, or of these with other parts of Scripture, composed for the use of churches as the Psalms of Tate and Brady, of Watts, &c.

Webster's Dictionary [3]

(1): ( n.) Especially, one of the hymns by David and others, collected into one book of the Old Testament, or a modern metrical version of such a hymn for public worship.

(2): ( v. t.) To extol in psalms; to sing; as, psalming his praises.

(3): ( n.) A sacred song; a poetical composition for use in the praise or worship of God.