Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. pūrĭtas, ātis, f. [purus], cleanness, purity (post-class.).
2. pūrĭtas, ātis, f. [pus], purulency (post-class.): sanguinis, Cael. Aur. Tard. 5, 4, 35.