Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. pĕtăsuncŭlus, i, m. dim. [petaso], a little leg or pestle of pork: siccus petasunculus, Juv. 7, 119.
2. pĕtăsuncŭlus, i, m. dim. [petasus], a small travelling-cap, Arn. 6, 198.