French linguist André Martinet used the term to refer to the two levels of structure in which language is organized: speech can be analyzed into the meaningful forms of language (i.e. morphemes, words, etc.), and this constitutes a “first” articulation; these units are then capable of further analysis into the meaningless sound units of language (i.e. phonemes), and this constitutes a “second” articulation. A corresponding term in more widespread use is duality of structure.