This paper seeks to redefine apposition, a term that is often used in the literature with a remarkable lack of precision. Starting from paradigmatic instances of apposition (Romulus, the legendary founder; Santiago, the capital of Galicia), the main resemblances to the paradigm are analysed in an attempt to measure the validity of a general syntactic relation that is often put on a par with co-ordination and dependency. Paradigmatic appositions and other related nominal patterns are shown to be structures of nonrestrictive modification (i.e. not really appositions) which are best understood in reference to the concept of a Local Domain. The second unit of these structures has its scope in the local domain of the first unit, of which it is an expansion, not in the larger domain of the sentence. By contrast, most instances of non-nominal apposition (e.g. He ran – absolutely raced – up the hill; Burton-Roberts, 1975) are seen as true appositions, as defined in this paper, namely as structures whose two units relate independently to a Sentence Domain without forming a superordinate node in it. Crucial to the distinction between the Local and the Sentence domains is the role of intonation boundaries. These are strongly obligatory only with those structures which have been considered paradigmatic appositions in the literature (Romulus, the legendary founder), and their role is to isolate the second unit within them from the remainder of the sentence, thus preventing it from having a function in it. The intonation boundaries are also responsible for the most distinctive feature of these structures, namely the predicative relationship binding the two units together (Dupont, 1985; Koktová, 1985; Longrée, 1987; Forsgren, 1988).