Whenever we hear (or see) a word or string of words of the language that we speak, our minds perform a special kind of computation on the expression, assigning it a syntactic structure that corresponds to a particular meaning. Consider the deceptively simple example of the orthographic form fish. We can use this orthographic form by itself to represent a sentence, defined at this preliminary point as a linguistic expression that begins with a capital letter and ends with a terminal punctuation mark (period, question mark, or exclamation point):

(1) Fish!

(1) can be assigned more than one interpretation because fish can designate either a verb or a noun. Under both interpretations the expression has the same pronunciation (whose representation is called Phonetic Form (PF)). Syntactically, however, there are two distinct linguistic representations for (1), one as a verb and the other as a noun. These representations correlate with the different interpretations of (1). In this way, the syntax provides a structural basis for the representation of meaning. This aspect of meaning is called Logical Form (LF). Ambiguity arises when a single PF corresponds to more than one LF. In this case, (1) is structurally ambiguous because its ambiguity derives from a difference in syntactic structure – i.e. whether the PF of (1) is construed as a verb (labeled V) or a noun (labeled N).