1. Excessively ingratiating or insincerely earnest: was annoyed by the unctuous waiter.
a. Containing or composed of oil or fat.
b. Having the quality or characteristics of oil or ointment; slippery.
3. Abundant in organic materials; soft and rich: unctuous soil.
[Middle English, from Old French unctueus, from Medieval Latin ūnctuōsus, from Latin ūnctum, ointment, from neuter past participle of unguere, to anoint.]
unctu·ous·ness, unc′tu·osi·ty (-ŏsĭ-tē) n.
Synonyms: unctuous, fulsome, oily, smarmy
These adjectives mean insincerely, self-servingly, or smugly agreeable or earnest: asked a favor in an unctuous tone of voice; gave the dictator a fulsome introduction; oily praise; smarmy self-importance.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.