根据Quirk，Greenbaum，Leech, Svartvik(1972)，衔接被笼统地定义为语篇中能够将一个句子与其前后句子 连接起来的某些词或语法特征。Gutwinski( 1976)试图将衔接置于一个多层框架之中，重点研究衔接在文体学方面的应用。Beaugrande和Dressler( 1981)指出衔接指的是表层语篇的语言成分，即人们听到或看到的实在语词在一个序列、在语言的语法规则基础上有意义地互相连接的方式。但论及衔接最著名的著作是Halliday 和Hasan的《英语的衔接》，他们认为语篇织体是由语篇中表示语义和语法关系的词项构成的，他们将这种关系称之为衔接纽带并将其分为五类：照应（reference)、替代 (substitution)、省略（ellipsis)、连接（conjunction)和词汇衔接（lexical cohesion )。在Halliday和Hasan等人看来，衔接是生成语篇的必要条件之一，尽管有些学者如Michael Hoey 就前者对衔接的分类和词汇衔接的语篇功能持不同见解,但他认为词汇衔接在语篇章组织方面起着最重要的作用。1.  词汇衔接语篇中跨越小句或句子的两个或多个词项之间有意义练习时就产生了词汇衔接，换言之，词汇衔接指通过词汇在语篇中建立一个贯穿语篇的衔接链，从而达到语篇的语义连贯。Hoey (1991)认为，衔接在很大程度上是词汇关系而非语法产物，词汇关系是唯一有系统 地构成多重关系的衔接方式，词汇衔接是创造语篇织体（texture )的主要手段。Halliday和Hasan (1976)对七篇不同类型语篇中的各种衔接手段进行分析后的结果表明，如果连接不算在内，由词汇构成的衔接纽带占近50%。他们将词汇衔接分为两种：（reiteration)和同现(collocation) 。这里的复现大致相当于Hoey (1991)所说的重复 (repetition)。复现包括重复（repetition)、同义词（synonym)或近义词 (near synonym)、上下义词（hyponymy )、泛义词（general words)等的重复。例如：〈1〉At his feet, now，were ants trickling back with pink fragments in their mouths，and there was a fresh acid smell in his nose.<2>He sternly controlled the uselessly convulsing muscles of his empty stomach， and reminded himself that the ants must eat too!在这里，第〈1〉句中的ants与第〈2〉句中的ants属于词的重复。下面是一个使用同义词产生衔接的例子： The soldier ants formed the flanks；the workers were in the middle.在这里，workers是soldier ants的同义词。在下面的例句中，我们可以看到词的上下义关系、泛义词构成的衔接：〈1〉He bent over the bones and touched the sockets in the skull：that was where the eyes were，he thought incredulously，remembering the liquid dark eyes of a buck.〈2〉That morning，perhaps an hour ago，this small creature had been stepping proud and free through the bush，felling the chill on its skin even as he himself had done，exhilarated by it.〈3〉Proudly stepping the earth, frisking a pretty white tale，it had sniffed the cold morning air,〈4〉 Walking like kings and conquerors it had moved freely through this bush，where each blade of grass grew for it alone，and where the river ran pure sparkling water for it to drink.〈5〉And then—what had happened? Such a sure swiftfooted thing could surely not be trapped by a swarm of ants.