FROM STRONG’S GREEK DICTIONARY (1890)

Strong’s Greek Dictionary (1890) — public domain, printed whole.

psallo ψάλλω — psal'-lo — probably strengthened from psao (to rub or touch the surface; compare 5597); to twitch or twang, i.e. to play on a stringed instrument (celebrate the divine worship with music and accompanying odes):--make melody, sing (psalms).

see GREEK for 5597