Semantics versus Syntax

Syntax refers to the grammatical structure of a language. For example, the English language includes nouns, verbs, adverbs, and adjectives. Depending on the position and conjugation of the words in a sentence, the sentence may have correct syntax, but still be nonsensical because of the logical content of the sentence. The canonical example is "Colorless green dreams sleep furiously," which uses valid syntax--[adj] [adj] [noun] [verb] [adverb]--but is nonsense because it violates several rules of semantics.

Semantics, therefore, refers to the logical content of a sentence. As we can see, "Colorless green dreams sleep furiously" could be translated into many languages (Les rêves verts sans couleur dorment furieusement), but still have the same problems of semantics: green and colorless are mutually contradictory attributes, while it is absurd to speak of dreams sleeping, even in a poetic sense.