Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
serro, āre, v. a. [serra], to saw, to saw up, saw in pieces (late Lat.): pali serrantur, Veg. Mil. 2, 25; Hier. in Isa. 15, 57, 1; Vulg. Isa. 41, 15; Ambros. in Isa. 4, 10, 15.