Language is containing a number of elements which related to each other in very specific ways on different levels. The principal function of language is to express meanings, and to convey these to someone else. There are two points of view in studying a language based on Saussure, they are diachronic point of view and synchronic point of view. Comparing with two different words used by two different groups of people speaking different language, sometimes they express a similar or identical meaning by using similar sounds. Perhaps, it occurred because there is some natural connection between the meaning and the form that is being used to express it. In other case, maybe the similarity says something about some kind of historical connection between the two languages.
Sir William Jones introduced the concepts of language relationship and protolanguage. First, he said that language relates each other. It means that if two languages have a common origin, they belong to a single family of language. Second, he said about protolanguage. It means that when there are three languages were derived from some other language, there was some ancestral language from which all three were descended by changing in different ways. The concepts of protolanguage and language relationship both rest on the statement that language changes. Protolanguage produced a number of different daughter languages. When protolanguage was replaced by its daughter language, it’s not mean that a protolanguage die out. Some language died out because their speakers die out or they abandon their own language. People’s attitudes to language change are fundamentally the same. People everywhere tend to say that the older form of a language is in some sense better than the form that is being used today. There are three ways in which new terminology, they are copying or imitating, adapting and extending meaning.
Crowley, Terry. 1997. An Introduction to Historical Linguistics. Oxford University Press: Australia.