Psalm
Old English (p)sealm, via ecclesiastical Latin from Greek psalmos ‘song sung to harp music’, from psallein ‘to pluck’.
wiktionary
From Middle English salm or psalme, from Old English psealm, later reinforced from Old French psalme (modern French psaume), both from Latin psalmus, from Ancient Greek ψαλμός(psalmós, “the sound emanating from twitching or twanging perhaps with the hands or fingers, mostly of musical strings”) (from ψάλλω(psállō, “to make a sound by striking, touching, plucking, rubbing, twanging, or vibrating”)), but later in New Testament times the meaning of ψαλμός(psalmós) evolved from its Classical meaning of "a tune played to the harp" to a more general tune that could be played with any instrument; even a song sung with or without musical accompaniment. By the Byzantine Period, it lost all of its instrumental nuances.
etymonline
psalm (n.)
"sacred poem or song," especially one expressing praise and thanksgiving, Old English psealm (West Saxon sealm; Anglian salm), partly from Old French psaume, saume, and partly from Church Latin psalmus, from Greek psalmos "song sung to a harp," originally "performance on stringed instrument; a plucking of the harp" (compare psaltes "harper"), from psallein "play on a stringed instrument, pull, twitch" (see feel (v.)).
Used in Septuagint for Hebrew mizmor "song," especially the sort sung by David to the harp and collected in the Old Testament Book of Psalms. Related: Psalmodize. After some hesitation, the pedantic ps- spelling prevailed in English, as it has in many neighboring languages (German, French, etc.), but English is almost alone in not pronouncing the p-.
