Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
faecŭla (also fēcŭla, and contracted faecla,Cael. Aur. Tard. 2, 1), ae, f. dim. [faex], burnt tartar or salt of tartar, deposited in the form of a crust by wine (used as a condiment or as a drug), Lucr. 2, 430;Hor. S. 2, 8, 9;Scrib. Comp. 226 al.