Lewis & Short

uxorcŭla, ae, f. dim. [uxor], a little wife (ante- and post-class.): erat ei uxorcula satis quidem tenuis, App. M. 9, p. 219, 8.
As a term of endearment: mea uxorcula! Plaut. Cas. 4, 4, 19; 5, 2, 38; Varr. ap. Non. 83, 25.