Cheshire

To smile smugly or mischievously. The term was popularized by the character in Lewis Carroll's Alice's Adventures in Wonderland. I knew he had a prank planned for April Fools' Day when he arrived at work grinning like a Cheshire cat.

Fig. smiling very broadly. (Alludes to a grinning cat in Alice's Adventures in Wonderland.) There he stood, smiling like a Cheshire cat, waiting for his weekly pay.

a very wide smile I just presumed he'd got the job because he walked in here with a grin like a Cheshire cat.

Smile broadly, especially in a self-satisfied way. For example, John ended the set with a beautiful serve, an ace, and couldn't help grinning like a Cheshire cat . The ultimate origin of this expression, appearing in print since the late 1700s, is disputed, but its most famous exponent was Lewis Carroll, in whose Alice's Adventures in Wonderland the grinning cat gradually vanished from view, with its grin the last part to vanish.

Having a perpetual, mischievous grin, one that is often indistinguishable from smugness. Although the Cheshire cat is best known as a character in Lewis Carroll's Alice's Adventures in Wonderland, it appeared much earlier in popular English culture, so the phrase may have originally referred to cheese made in the country of Cheshire and molded roughly to resemble a grinning cat. Lewis Carroll's feline had the ability to disappear until only its smile remained. The cheese variety would be sliced from hind end to front, which similarly gave the impression that its smile—if cheese showed emotion—would be the last to go.