SOAPIEST
SOAPY
buttery, fulsome, oily, oleaginous, smarmy, soapy, unctuous
(adjective) unpleasantly and excessively suave or ingratiating in manner or speech; “buttery praise”; “gave him a fulsome introduction”; “an oily sycophantic press agent”; “oleaginous hypocrisy”; “smarmy self-importance”; “the unctuous Uriah Heep”; “soapy compliments”
saponaceous, soapy
(adjective) resembling or having the qualities of soap; “a soapy consistency”
Source: WordNet® 3.1
Adjective
soapiest
superlative form of soapy: most soapy
Source: Wiktionary
SOAPY
Soap"y, a. [Compar. Soapier; superl. Soapiest.]
1. Resembling soap; having the qualities of, or feeling like, soap;
soft and smooth.
2. Smeared with soap; covered with soap.
Source: Webster’s Unabridged Dictionary 1913 Edition