Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
flŭesco (or fluisco), ĕre, v. inch. n. [fluo], to become fluid, to melt, dissolve (late Lat.): salem in aqua fluescere, Aug. Civ. Dei, 21, 5 fin.: nivem, id. ib. 7 med.