The meanings of words should not be allowed to vary or change.
Language changes all the time, words get different meanings and use of words changes. English use to say, Saw you my son. Instead of what is now, did you see my son? Another example is pronouncing the K in the word Knee, this happened earlier and is not pronounced today.
Examples of change in the meaning of words, Nice mean silly in old French, Foolish in medieval English and means modest today. Speakers of different dialects will always understand one another even if they follow different patterns of usage (Baur & Trudgill, 1998).
Baur, L., & Trudgill, P. (1998). Language myth. In Baur, & Trudgill, The meaning of words should not be allowed to vary or change (p. 7). London: Penguin Books.