To emphasize this relationship, Saussure calls the sound-image (the word) the “signifier” and the concept (its referent) the “signified.” The letters T-R-E-E signify the concept of a tree. This combination is a sign.
Saussure notes that the relationship between the signifier and the signified is arbitrary. That is, nothing about a tree indicates that it should be represented by particular sounds, syllables, or letters. “Arbitrary” does not mean that the choice is left to the speaker: “the individual does not have the power to change a sign in any way once it has become established in the linguistic community” (Saussure, 2011). Instead, Saussure means the relationship is “unmotivated,” there is no “natural connection” between the signifier and signified (2011). The arbitrary nature of signs is why different languages have different words for essentially the same concept (tree, arbre, árbol, baum).
Saussure further proves that not only does the signifier change across language systems but the signified itself can also change. When hearing the word tree, a person who grew up near the redwoods of the Pacific Northwest of the U.S. likely pictures something different than someone who grew up in the Sahara Desert or in Japan.
Some words are partially motivated. For example, onomatopoeia are in part derived from the sound they aim to describe. However, different languages have different words for the same sound — English dogs say “bow-wow” while French dogs say “ouaoua” — so onomatopoeia are still shaped by the language system in which they arise.
Types of signs
Working on the other side of the Atlantic, Charles Peirce (1839–1914) was another important figure in early semiotics. Peirce named three kinds of signs based on the relationship between the signifier and signified: symbol, index, icon. In the case of the symbol, there is no connection between the expression and its content; it is “unmotivated,” in Saussure's terms. Its meaning is learned but not derived from the object itself.
An index, Peirce explains, “necessarily has some quality in common with the Object, and it is in respect to these that it refers to the Object” (The Essential Peirce, Vol. 2., 1998). To use Sturrock’s example, a “ring round the sun” is a sign of rain. This sign is “naturally” derived from what it represents, but it is still open to interpretation based on cultural norms, individual knowledge, and the reason for which an individual may interpret the sign — “for practical reasons, if he is a farmer, or for more loosely communicative ones, to display perhaps an acquaintance with weather-lore” (Sturrock, 2008).
An icon, also called a likeness, directly imitates what it represents. A painting or photograph of a tree is not a tree, but it signifies a tree through imitation. This example helps us recognize that signs need not be linguistic; semiotics addresses signs that are verbal, pictorial, gestural, and more.
La parole and la langue
To better describe language as a system, Saussure draws a distinction between la langue (language) and la parole (word). Parole is the individual action of speech (whether in written or verbal form), whereas langue describes the full catalog of options and rules, the language system at large. As Sturrock writes,