Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ponduscŭlum, i, n. dim. [pondus], a small weight (post-Aug.): saxi, Col. 12, 51: si cooriatur procella, apprehensi pondusculo lapilli (apes) se librant, Plin. 11, 10, 10, § 24.