Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
algus, ūs, m., acc. to Prisc. p. 699 P.; Rudd. I. p. 122, or algu, n., acc. to Charis. 23; 98 P.; cf. Schneid. Gr. 2, 342 sq. [algeo], the feeling of cold (subjective), coldness (usu. only in the abl.; hence the form of the nom. is uncertain; ante-class. for the class. algor).