This introductory chapter presents an overview of the key concepts discussed in the book. The book seeks to develop a synchronic model of the interface between lexical semantics and pragmatic interpretation. It proposes a syntactic, semantic, pragmatic and diachronic analysis of four particles that are highly frequent in modern French, viz. the so-called phasal adverbs deja, encore, toujours, and enfin. First, the chapter explores the extent to which their different contemporary uses can and should be attributed to the existence of so many different coded meanings. Secondly, it discusses phasal adverbs in their various uses convey certain elements of meaning that are of a non-truth-conditional nature. Thirdly, the chapter examines how new uses of words become entrenched in a language. The question of entrenchment of new uses involves investigating how and why pragmatic elements of utterance interpretation may become semanticized. It involves a diachronic view on the semantics/pragmatics interface.