Here's a term that makes me cringe when I hear it. "Fleshing out" a character gets thrown around quite a bit these days. I don't object to the idea of layering a character, as much as the terminology. We are creating fictional characters - they have no flesh. They can have characteristics heaped upon them aplenty but they are fleshless.
When I read, I take the bits and pieces given to me by the author and mold my own character. It's more of a wisp of air than flesh. It's an interpretation of features, actions and observations from other characters. I have to admit that I often rewrite a character in my head. The author may have described the MC as a tall blond bombshell with bravado to spare. If I like the story but object to a character, I very easily substitute my own imagined description. When I was a teenager and devoured romance novels, I usually changed the heroine to better fit my own characteristics. (She never was blond or tall in my mind.)
A writer can describe a character with witty and precise words. But, in the end, it's the imagination of the reader that defines the character. Your perfectly "fleshed" out character may end up resembling someone from their childhood or bagger at the grocery store that put a can on top of their bread.
Terms that make you cringe, twitch or gag?