Selah
Easton's Dictionary
Smith's Dictionary
This word, which is found only in the poetical books of the Old Testament, occurs seventy-one times in the Psalms and three times in Habakkuk. It is probably a term which had a meaning in the musical nomenclature of the Hebrews, though what that meaning may have been is now a matter of pure conjecture. (Gesenius and Ewald and others think it has much the same meaning as our interlude,—a pause in the voices singing, while the instruments perform alone.)
International Standard Bible Encyclopedia
se'-la.
See MUSIC, II, 1.