Number Two ( 2) Language is Arbitrary in Nature
One word describing an object may very well be another—such as the word door could as easily have been assigned to a window.
The arbitrary nature of language can be called into question since objects have names based on whatever they were used for initially; however, for this brief treatment, it stands as a ruler for language.
The evidence that language is arbitrary is overwhelming. The fact that there are literally thousands of languages attests that anything can be called anything! Take the word Yes. In English, yes, means to agree or answer in the affirmative. In Spanish, Si is to agree or answer in the affirmative. In French, Qui is to agree or answer in the affirmative. In Xhosa it is Ewe. Depending on what language a person uses, what English people call yes could be any sound.
Yes, in Klingon it is HIja. Even fictional languages must meet the five criteria to appear believable.