Tacky means showily cheap and lacking taste, or slightly sticky. A tacky souvenir, tacky decorations, still tacky to the touch.
The paint sense is technical and useful: tacky means dry enough to touch and not dry enough to recoat, which is the window a decorator waits for. The taste sense is American in origin and much more common now.
1adjectivetackyShowily cheap and lacking taste.
“She thought the gold wallpaper and plastic palm trees in the hotel were really tacky.”
2adjectiveslightlySlightly sticky.
“The glue was still tacky, so she held the pieces together for another minute.”
tacky is a quality of taste, or of stickiness.
Tack plus -y, from tack meaning a small sticky point. The sense of vulgarity is nineteenth-century American.
Proto-Indo-European
*dHgʰ-n-
Frankish
*takkō — twig, branch, shoot
Middle English
tak
English
tack
English, today
tacky
Built from
From tack + y. tack comes from Middle English tak, takke (“hook; staple; nail”), from fro-nor - taque (“nail, pin, peg”), from Frankish takkō (“twig, branch, shoot”), of unknown origin, but possibly from Proto-Indo-European dHgʰ-n-, from the root déHgʰ- (“to pinch; to tear, rip, fray”). Cognate with stq Takke (“bough; branch; twig”), West Frisian takke (“branch”), tûk (“branch, smart, sharp”), Dutch tak (“twig; branch; limb”), {{cog|de|
Etymology from Wiktionary, CC BY-SA