- Resembling or having the properties of oil : oily ; also : containing or producing oil
- Marked by an offensively ingratiating manner or quality
I became aware of the word in an EW review of the new season of Damages:
More mystery envelops yet another new character — Deadwood’s Timothy Olyphant, as an oleaginous member of Ellen’s grief-counseling group.
The writer means it in the second sense. It’s a lovely word, and a nice alternative to the similar unctuous. Another reason I’m happy to have so many words in English.