What is giving a name to meaning or definition?
nomenclature

Main question
#1. But, If "something" has meaning or a definition, does changing the name of it change the meaning and definition?

Main question
#2. And, is there such a word, concept or title of a philosophy that describes changing the name of something already defined?

Example: On one hand, "human" coined about 500 years ago and homo sapian coined about 300 years ago.

Main question
#3. However, on the otherhand, if a new word is coined and by popularity perhaps over takes the old word, or is considered to have stolen the definition of the old word: is there something specific this is called? Basically, viewing the old name void or invalid.

Just a thought:
There is "something " then someone decided to name it, versus, we will call it "something " then give it definition or meaning. Compare the thought of first naming a child, then have sex to produce the child versus, first having a baby then giving it a name.