This article is a critique of the traditional semantic approach of extension and meaning variation. In a first part Bianchi looks at the traditional approach of ambiguity (homonymy and polysemy) and at semantic flexibility (figurative meaning, metaphorical uses). She criticizes one of the central views of traditional semantics which claims that linguistic expressions have fixed meanings and specific truth conditions. She chooses a different descriptive frame: the contextualist frame which claims that meaning varies indefinitely according to the linguistic and extralinguistic context. Coherence is the result of the association of a linguistic expression 'w' to a collection 'C' of referents or to contexts. These contexts are related by similarity which allows for meaning extension: A word used in a specific context can be used in a new context which is similar to the first context. In the interpretation of a metaphor like 'Jean est un tigre' the receiver has to discover the 'aspect' under which John is similar to a tiger. The similarity relation is motivated by a relevant context. It must be accessible to the hearer/reader, who must be able to identify this relationship easily and quickly. (Sabine De Knop)