Opp. of "oxymoron"

[Jesse Sheidlower]

A colleague just asked if there is a word for the opposite of "oxymoron,"
referring to the use of two terms of similar meaning, like perhaps "dead
loss." The problem with terms like "tautology" or "redundancy" is that
these are generally used in reference to disapproved usages, and we're
looking for a term that refers in a favorable way to such constructions
esp. when used for deliberate rhetorical effect.

Any ideas?

Jesse Sheidlower