This idiom is common in mathematics, where it's called a conjugate.
Any time you have an element, y, of a group, the action of pre-composing with any other element, x, and post-composing with x's inverse to get xyx^{-1} is called conjugating, and the result is a called a conjugate of y.
Any time you have an element, y, of a group, the action of pre-composing with any other element, x, and post-composing with x's inverse to get xyx^{-1} is called conjugating, and the result is a called a conjugate of y.
http://en.wikipedia.org/wiki/Conjugation_(group_theory)