title_body: By what means might the roots "let" and "ly" mean the same thing in a naturalistic conlang? I apologize for how this question may be perceived. I am casually learning linguistics with no curriculum. I can understand that this question may have many possible answers, but I am not quite sure how else to ask this question. I can also understand if all that may be provided to me is some resource on lists of natural ways languages evolve.
  
  Basically, I've come up with two place names, "Yallet" and "Helverly". I'm trying to create enough of a naming language that would allow me to create names that seem to occur naturally in the setting.
  
  Both Yallet and Helverly are locations, and so I was wondering if there was a way for the root "let", meaning town, to conceivably evolve to "ly".  
  
  Can this evolution happen naturally? If so, I would happily read on such transformations. If not, I would be very appreciative of an explanation as to why it would not be a natural evolution.
upvoted_answer: It is a two-step process, and both steps are very natural and frequently encountered in natural languages. The steps may occur in the other order as well, but the order here deems more common to me.
  
  
  Loss of the final stop let -> le. This occurs very often, French is a prominent example of this because the final stops are preserved in writing, but lost in pronunciation (with some exceptions when there is a following vowel).
  A vowel shift le -> li, in this case a raising. Again, this step is very natural because /e/ and /i/ are neighbouring vowels in the vowel diagram.
  
  
  These two steps use your assumption that let is the older form that evolves into ly. A more sophisticated construction could assume a common ancestor for both forms, e.g., lit that evolves to li by the loss of the final consonant and to let by lowering the vowel.
  
  EDIT: As you are generally interested in sound laws, there is a resource named Index Diachronica that lists a lot of sound changes collected from many sources.