Comments:EDT 126-127, ЭСТЯ 1, 587-588. The original meaning was certainly 'to extend, prolong' - as seen also from the derivatives *ula-m 'still more, continuously' (ЭСТЯ 1, 591) (whence Mong. *ulam id., see TMN 2, 107), *ula-ju 'still more, as much as', *ulag 'order, relay, relay station' (ЭСТЯ 1, 588-590) (whence Mong. *ulaɣa id., see TMN 2, 106, Щербак 1997, 161; with the meaning 'relay horse' penetrated into some Ugric languages, despite Sinor 1965, 312-315 who proposed an opposite direction of borrowing);