Oxymoron is a conjunction of seemingly contradictory notions. It is a combination of two words in which the meaning is opposite in sense: e.g. speaking silence, cold fire, living death. “And faith unfaithful kept him falsely true” (A.Tennison).
Trite oxymoron. E.g. awfully beautiful.
Close to oxymoron is paradox - a statement that is absurd on the surface. E.g. War is peace. The worse - the better.
If the primary meaning of a qualifying word is changed the stylistic effect of oxymoron is lost. In oxymoron the logical meaning holds fast because there is no true word combination.