An important part of Ferdinand de Saussure's linguist theory in "Course in General Linguistics" is what he terms "The arbitrary nature of the Sign". Following his discussion about the nature of the linguistic sign de Saussure argues that the relations between the absolute majority of signifies to signified is arbitrary. With the small exception of onomatopoeia (words that sound like what they refer to) There is no imperative connection between words and their meanings. This can be easily proved through the fact that different languages have different words to refer to the same things.
The arbitrary nature of the sign doesn't mean that it is false or that you can just use any word you want to refer to whatever you want. What is does mean is that language is a self contained structure built on inner relations between words as opposed to external relations between words and things. One interesting implication of the arbitrary nature of the sign is that language is not built to meet a preexisting reality, but rather the other way around.