Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* frātercŭlo, āre, v. n. [fraterculus], a word comically formed by Plautus, after the analogy of sororiare, and also used of the breasts, to swell up alike (v. sororio), Plaut. Fragm. ap. Fest. p. 297 Müll.; cf. also FRATRARE.