trea·cly \-k(ə)lē, -li\adjective Etymology:treacle + -y : resembling or held to resemble treacle (as in quality or appearance) : composed of treacle : as cloying or sticky as treacle < saturated with black treacly oil — Audrey Barker > < purveyors of treacly Pollyannaish fiction — Nashville Tennessean > < treacly sentimentalities >