The LJLA var. תושש is almost certainly a hypercorrection from a misunderstood form of ntš. Page refs. in other dictionaries: DJPA: 594a; Jastrow: 1705; Levy Ch-W: 2:565;
btšw, btšwt adv. exhausted tšw, tšwtˀ n.f. feebleness tšyw, tšywtˀ n.f. weakness (??) tššw, tššwtˀ n.f. feebleness