Lewis & Short

bellŭlus, a, um, adj. dim. [bellus], pretty, fine, lovely, beautiful (ante- and post-class.); edepol haec quidem bellula est, Plaut. Mil. 4, 1, 43; id. Cas. 4, 4, 22; id. Poen. 1, 2, 134; Inscr. Murat. 1514, 3.
Adv.: bellŭlē, prettily, finely, etc., Plaut. ap. Paul. ex Fest. p. 36 Müll.; App. M. 10, p. 246, 23; 11, p. 272, 34.