Lexical cohesion is about meaning in text. It concerns the way in which lexical items relate to each other and to other cohesive devices so that textual continuity is created. The seminal work on lexical cohesion is Halliday and Hasan’s (1976) Cohesion in English, where it is nevertheless given the shortest treatment of the five types of cohesion identified by the authors. According to Halliday and Hasan (1976), lexical cohesion concerns two distinct but related aspects: reiteration and collocation. Reiteration is “the repetition of a lexical item, or the occurrence of a synonym of some kind, in the context of reference; that is, where the two occurrence have the same referent” (Halliday & Hasan 1976:318–9), while collocation is the use of “a word that is in some way associated with another word in the preceding text, because it is a direct repetition of it, or is in some sense synonymous with it, or tends to occur in the same lexical environment” (Halliday & Hasan 1976:319). Collocations may include any words that are in some sort of semantic relationship, although Halliday and Hasan (1976) draw special attention to superordinates, hyponyms and antonyms. It is to be noted that the conception of collocation, which is exemplified as operating primarily across clauses, is different from the current understanding of the term in corpus linguistics, as is illustrated in some of the contributions to the present issue.