I find that I have a sort of "personal dictionary" of words that I like to use. I use "salient" a lot. I use "hence", "perhaps", "incapable", "fortuitous" frequently. I store a sort of "cache" of words - both common and uncommon - that I use regularly as a part of how I speak.
I figure this is the case for everybody - certain friends use some words more than others in regular communication, etc. I'm sure you have your own set of words that you tend to "fall back" on.
So the question is - what is the name for this cache? What is the word or phrase for "collection of words or phrases a person commonly uses to communicate"?