Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* pŭellasco, ĕre, v. inch. n. [id.], to become a girl, i.e. to grow girlish or effeminate: etiam veteres puellascunt et multi pueri puellascunt, Varr. ap. Non. 154, 8 sq.