There is a general consensus that pairs like "il braccio / le braccia" belong to a non-productive inflectional class, often endowed with a special collective interpretation. But this leads to a number of problems, some of which have remained unnoticed: the coordination of two such nouns in the singular triggers plural masculine agreement rather than the expected feminine; a singular feminine pronoun can refer to a plural in "-a" only with a distributive interpretation; alternative plurals in "-i" are not blocked even though they should be. This suggests that plurals in "-a" are in fact inherently plural stems, lexically associated with feminine gender and semantically, not just grammatically, plural. As derived "pluralia tantum", they do not block the inflectional plurals of the primary stems. Besides, they display a variety of interpretations which suits a lexical plural better than an inflectional class. Still, there is a (weak) semantic basis for inclusion in this class: reference to a plural set whose members are not distinguishable from each other. This restriction further suggests that plurals in "-a" make up a distinct lexical class.