Selah
SELAH (sē'la, Heb. sālal, to lift up). A term occurring seventy-one times in the Psalms and also in Hab.3.3, Hab.3.9, Hab.3.13. The meaning of selah is unknown. It is generally believed that its usage was that of a musical or liturgical sign. The LXX seems to understand it as a direction to the orchestra—“lift up”; i.e., play the instruments while the singers are silent. The Jewish Targums and Jerome translate it “for ever,” but there is no support for this. Jacob of Edessa (a.d. 640-708) compared it to the Amen sung by the Christians after the Gloria. Perhaps selah was used in a similar way, as a signal for the singing of some sort of doxology or benediction after psalms or parts of psalms divided for liturgical use. The word usually occurs at a place where a very significant statement has been made, making that a good place for a break or pause. It is believed that “selah” was introduced during the late Persian period.
International Standard Bible Encyclopedia (1915)
se’-la.
See MUSIC, II, 1.