Unctuous is used to describe someone who speaks and behaves in a way that is meant to seem friendly and polite, but is unpleasant because it is obviously not sincere.

An example of unctuous in a sentence: The politician seeking higher office put forth an unctuous effort to win over the voting public.

Nowadays, "unctuous" has a negative connotation, but it originated in a term describing a positive act, that of healing. The word comes from the Latin verb unguere ("to anoint"), a root that also gave rise to the words "unguent" ("a soothing or healing salve") and "ointment." The oily nature of ointments may have led to the application of "unctuous" to describe things that are afflicted with an artificial gloss of sentimentality. An unctuous individual may mean well, but his or her insincere earnestness may leave an unwelcome residue with others, much like some ointments.

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