Soapy means tasting unpleasantly of detergent. A soapy taste, soapy water, tastes soapy.
The famous case is coriander, which tastes soapy to a minority of people because of a gene affecting how they smell certain aldehydes — the same compounds occur in soap, so the comparison is chemically exact. Soapy also means simply full of soap, and of a manner it means unctuous. Note soap; and that soapy dishes want rinsing.
1adjectivesoapyTasting unpleasantly of detergent.
“The glasses hadn't been rinsed properly, so the water tasted soapy.”
2adjectivefullFull of soap.
“She washed the dishes in hot soapy water.”
soapy is a quality of taste or lather.
Soap plus -y, from Old English sape. The word is Germanic and old.
Middle English
sope
English
soap
English, today
soapy
Built from
From soap + y. Compare German Low German sepig (“soapy”), German seifig (“soapy”), Swedish såpig (“soapy”). soap comes from Middle English sope. From Middle English sope, sape, from Old English sāpe (“soap, salve”), from Proto-West Germanic saipā, from Proto-Germanic saipǭ, from Proto-Indo-European seyb-, seyp- (“to pour out, drip, trickle, strain”). Cognate with Scots saip, sape (“soap”), stq Seepe (“soap”), West Frisian sjippe (“soap”), Dutch zeep (“soap”), German Low German Seep (“soap”), German Seife (“soap”), Danish sæbe (“soap”), Swedish såpa (“soap”), Norwegian Bokmål såpe (“soap”), Norwegian Nynorsk såpe (“soap”), Faroese sápa (“soap”), Icelandic sápa (“soap”), Finnish saippua (“soap”), Finnish suopa (“soft soap”). Related also to Old English sāp (“amber, resin, pomade, unguent”), Latin sēbum (“tallow, fat, grease”). See seep. Latin sāpō (“soap”) is a borrowing from the Germanic.
Etymology from Wiktionary, CC BY-SA