This Thursday, I will be performing in the world premiere of William Bolcum's Eighth Symphony, a work commissioned for the Tanglewood Festival Chorus and the Boston Symphony Orchestra. It is a contemporary setting of selections of William Blake's Prophetic Books (The Marriage of Heaven and Hell, Jerusalem and America: A Prophecy). What does this have to do with "unctuous". In Part 1, "Rintrah roars", the tenors sing the line: Now the sneaking serpent walks in mild humility. The marking for that is "unctuous". I don't pretend to be a Blake scholar, nor do I really grasp a tenth of all the symbolism in these selections, but I do find this particular marking to be a riot. So, on that note (pun intended), I bring you: unctuous.
Unctuous derives from the Latin "unctus" for the act of anointing or smearing. It is related to "unguent", the thing that is smeared. And since this word developed c. 1350, its etymology is not so disjointed. From the oily or soapy feeling of the unguent, to having similar characteristics of a unguent generally (greasy or oily), to general characteristics which may be construed as slippery, and from there is just an easy leap to smug or suave, as a form of a slippery attitude.
Oatmeal soap is less unctuous owing to to the rougher texture of whole oats in the bar. Ok, but I don't think we commonly use unctuous to describe things that are actually slippery. Oil unlike ice is unctuous. Ice can't be unctuous since it isn't viscous, nor does it feel slippery until you are slipping. Oil is always slippery. And, sorry for the graphic reference, so is mucus. More often, now, unctuous is used negatively to describe people. Car salesmen have a reputation for being unctuous. Plaintiff's counsel's unctuous courtroom demeanor detracted from his credibility. Too easy. So, let's go back to the Blake excerpt. I think the serpent is a direct reference to the serpent from the Garden of Eden, and that this character would be "walking in mild humility", belies a certain slick character to try to seduce the listener. Whether the tenors can pull that off, I let you know after Thursday.