Stage

Stage is a model-theoretic entity, introduced in Carlson (1977), which represents the manifestation of an object or kind in time and space (a 'spatiotemporal slice'). The subjects in (i)a refer to stages of the object John and the kind dog, respectively, to which a transient, temporary predicate applies.

(i) a	John was running b	dogs were running

A stage level interpretation is distinguished from an individual level interpretation: in (ii) John and dogs refer to an object and a kind rather than a spatiotemporal instance.

(ii) a	John is intelligent b	dogs are smarter than cats

Links
Utrecht Lexicon of Linguistics