What is structuralism in linguistics?
Linguistic structuralism began in Switzerland with Ferdinand de Saussure. His innovations changed linguistics from a purely diachronic study of the historic origins and progress of language, which was devoted to analyzing what was said (e.g., Indo-European or Basque). He initiated a synchronic study of language as discrete units in a specific time periods wherein words have relationship to other words. It is the relationship, the deep rules of relationship, or grammar, langue, that interested Saussure and became structuralism.
In Saussure's structuralism, the topic of conversation is set aside, the parole, as being arbitrary to the underlying properties that bind the constituent elements of language together. In other words, a sentence about the fuzzy softness of a cat has relationships between the constituent parts (signifiers) as does a sentence about the the characteristics of dark matter in the cosmos. Structuralists want to know and describe (not prescribe) the rules of these relationships in langue.