What is a Psalm?

The word, “psalm” is an old English word meaning (From Merriam Webster):

Middle English, from Old English psealm, from Late Latin psalmus, from Greek psalmos, literally, twanging of a harp, from psallein to pluck, play a stringed instrument

    And is used the translate the Hebrew word, mizmor (transliterated to English), meaning (Strong’s H4210): properly instrumental music; by implication a poem set to notes: - psalm.

    H4210 is derived from H2167, zamar (transliterated) meaning: A primitive root (perhaps identical with H2168 through the idea of striking with the fingers); properly to touch the strings or parts of a musical instrument, that is, play upon it; to make music, accompanied by the voice; hence to celebrate in song and music: - give praise, sing forth praises, psalms.

    Properly, then, a psalm is a poem that is sung or recited to the accompaniment of a stringed instrument.  Other instruments may be used, Psalms 150 lists: trumpet (shofar), psaltery (form of harp), harp, timbrel (tambourine), and organ (a reed instrument—pipe), but a psalm is not a psalm without a stringed instrument.

      One form of the harp, the kinnor, or lyre, as described by the book, Illustrated Manners and Customs of the Bible:

  A smaller lyre (kinnor) was considered to be the most sophisticated instrument.  Its shape and number of strings varied, but all types of lyres produced a most pleasing sound.  The lyre was used in secular settings (Isa. 23:16), but was welcomed in sacred use too.  It was the instrument David used to soothe King Saul.  Generally, this “little lyre” was played by stroking the strings with a plectrum, much as a guitar can be played with a pick.  However David seemed to prefer to use his hand instead (1 Sam. 16:16, 23; 18:10; 19:9).

      In Scriptural times, the people did not use intricate melodies and their instruments provided rhythm rather than melody.