I'm not a researcher, but what I remember from my studies is that what makes words change pronunciation and meaning is basically people and the use they make of these words. Then you indirectly have culture, places, etc where these people find themselves which will influence as well.
Even if we understand how these words do change, it's hard to create a word that doesn't respond to these factors or that ignores them because they are not predictable. Changes in meaning are really dependent on use and popularity and indeed, popular words will acquire new meanings or they will be adopted by other countries (many did with English words for example) in order to refer to a certain meaning.
With changes in culture, in technology, science, and society, words will inevitably change.
Changes in sounds are more regular and have less exceptions (real world ones still do), and this regularity is used by linguists, such as in the Comparative Method which "aims to prove that two or more historically attested languages are descended from a single proto-language by comparing lists of cognate terms."
However one of the principles of Sound Change is that Sound change is unstoppable: All languages vary from place to place and time to time, and neither writing nor media prevent this change. In conclusion, your objective might not be reachable.