Outside of the United States a treacle is a kind of syrup that is made of molasses and other ingredients. Inside the US, and outside as well, treacle can also be used to describe anything that is overly sweet or sentimental, perhaps to the point of annoyance or irritation.
Treacle also used to be the name of an anti-poison treatment.
Treacly is the adjective form, describing something or someone as overly sweet or looking like treacle. In this form it can make treaclier and treacliest.
There is even a section dedicated to deserts with entries like jam rolls, bread and butter pudding and treacle tarts. [Daily Mail]
This Christmas album is relentless shimmery treacle, so sticky and unpleasant it verges on the aesthetically violent, as effective as any weapon currently deployed by the Pentagon. [The New York Times]
To begin with Golem is an amiable, benevolent chap (achieved partly through his treacly voice, courtesy of Ben Whitehead, who does the voice of Wallace in the recent Wallace and Gromit video games). [The Telegraph]
The strings and guitar line get even treaclier, even more so when I realize it’s doing so in order to chase the vaguely-classical-guitar trend that lasted about a year. [Village Voice]
For my dessert choice of Eccles Cakes and Benedictine Cambridge Creams (creme brulee with East Lancashire’s favourite French herbal liqueur), head for Jerez in Andalucia for the sweetest, treacliest treat around – Pedro Ximenez sherry. [Manchester Confidential]
In what might be the treacliest (and saddest) “Wonder Years” episode of all time — and one that collected two Emmys for its writing and directing — Kevin’s quietly supportive math teacher Mr. Collins unexpectedly dies. [Washington Post]