IPA: /ʌŋkˈtʃuːs.nəs/
KK: /ʌŋkʧuəsnəs/
The quality of being excessively flattering or ingratiating, often in a way that is insincere or oily.
His unctuousness made it hard to trust his compliments.
Unctuousness is formed from "unctuosus" (from Latin, meaning oily or greasy) and the suffix "-ness" (meaning the state or quality of). The word describes the quality of being oily or greasy, often used metaphorically to refer to someone who is excessively flattering or ingratiating.
Think of the Latin word for oily, 'unctuosus', to remember that 'unctuousness' refers to the quality of being oily or overly flattering.