The grammatical tradition has excluded lexical plurals from the category of collective nouns on the sole basis of their morphology (no discrepancy between singular form and so-called plural reference); but this criterion has led to hesitations, some linguists including, for instance, cattle or people. This study therefore considers other, semantic, criteria to establish more convincingly whether lexical plurals that denote pluralities of entities may be collective nouns. Relying on distinctions between meronymy and (non-taxonomic) hyperonymy, collectiveness and cohesion, and (a) crew (collective sense) / (several) crew (uninflected plural), it concludes that they are definitely not collective nouns, but aggregate nouns (or senses of nouns). Two sets are established. Some, mainly denoting humans, typically originate in the collective sense of the noun through a coercion mechanism; the others, mainly denoting objects, result from an operation of abstraction. For some of these, the notion of “hyperonyms of plural classes” is put forward.