Pronunciation: (fī'lum),[key] —n., —pl.-laPronunciation: (-lu).[key] 1. Biol.the primary subdivision of a taxonomic kingdom, grouping together all classes of organisms that have the same body plan.
2. Ling.a category consisting of language stocks that, because of cognates in vocabulary, are considered likely to be related by common origin. Cf. stock (def. 13).