Lexical underspecification refers to the phenomenon that the relatively general meaning of a lexeme may be specified in a certain context.This phenomenon is seen as one of the problems left untouched in lexical semantics.The purpose of this study is find out the general mechanism for the specification of lexical meaning,i.e.how the specified meaning of a lexeme in a particular context is interpreted.In order to answer this question,a new discipline,the theory of lexical pragmatics,is introduced in this paper.Lexical pragmatics points out the limitations of the principle of compositionality and argues that pragmatic principles function even at the lexical level,as well as at sentence or discourse level.That is to say,in order to fully understand lexical meaning,it is necessary to activate both semantic and pragmatic principles.Lexical pragmatics tries to explain the interaction between semantic and pragmatic principles and to make account for the comprehension of lexical meaning.It is argued in this paper that the interpretation of lexical meaning involves two aspects.First,the semantic aspect.The semantic skeleton model of compositionality is adopted,which suggests that the semantic aspect of lexical meaning is regarded as the basic framework or guideline in the course of interpreting lexical meaning.Second,the pragmatic aspect.Context plays an important role in the compositional process itself.The specified meaning of a lexeme has to be "flesh out"or recovered by contextual enrichment.This kind of enrichment is completed through pragmatic inference,with the help of world knowledgy.This paper examines lexical underspecification that is ubiquitous in phrases of free combination,with the premodifier+noun head structure highlighted.In conclusion,the phenomenon of lexical underspecification is viewed in the communication process with the speaker and hearer at each end.On the one hand,the speaker uses underspecified linguistic representations to express his intentions.On the other hand,the hearer has to make inference to recover the specified meaning of what the speaker says by contextual enrichment.This kind of inference is constrained by the principle of relevance,i.e.people tend to achieve optimal relevance with the least effort spent in communication.Therefore,toward a full understanding of the meaning of a phrase as a whole,the mechanism includes cognitive and pragmatic principles,as well as semantic and compositional principles.