UNCTUOUSLY

unctuously, smarmily, fulsomely

(adverb) in an unctuous manner

Source: WordNet® 3.1

Etymology

Adverb

unctuously (comparative more unctuously, superlative most unctuously)

Insincerely and excessively charming

Source: Wiktionary

UNCTUOUS

Unc"tu*ous, a. Etym: [F. onctueux, LL. unctuosus, fr. L. unctus anointment, fr. ungere, unctum, to anoint. See Unguent.]

1. Of the nature or quality of an unguent or ointment; fatty; oily; greasy. "The unctuous cheese." Longfellow.

2. Having a smooth, greasy feel, as certain minerals.

3. Bland; suave; also, tender; fervid; as, an unctuous speech; sometimes, insincerely suave or fervid.

– Unc"tu*ous*ly, adv.

– Unc"tu*ous*ness, n.

Source: Webster’s Unabridged Dictionary 1913 Edition