coco, my favorite word for this is contranym (said Tom contrarily).

b97, who says sycophancy isn't a word??
1. The trade or occupation of an informer; calumnious accusation, tale-bearing. Now only in Gr. Hist.
2. Mean or servile flattery; the character of a mean or servile flatterer.

say, have you ever noticed how many great words there are in the sycophant family?