Go onto your texture pack, create or go into the folder called "lang"
\assets\minecraft\lang < folder location
then go find want you want to change, either by searching on the left (e.g. if i wanted to change respawn to revive, i would look for deathScreen.respawn) or look on the right < easier for beginners (e.g. if i wanted to rename baked potato to jacket potato i would search for "Baked Potato"
Then when you have renamed it, it should look a little bit like this
"deathScreen.respawn": "[what you renamed]"
Now click save, and test it in game!
Extra info:
Use eclipse for easier editing .json files
DO NOT REPLACE ANYTHING BUT THE WORDS IN QUOTATION MARKS
Pretty sure special characters aren't possible
