Cheshire cat

noun
1.
a constantly grinning cat in Lewis Carroll's Alice's Adventures in Wonderland.
Idioms
2.
grin like a Cheshire cat, to smile or grin inscrutably.
grin like a cheshire cat in Culture
Cheshire cat [(chesh-uhr)]

A cat with an enormous grin encountered by Alice in Alice's Adventures in Wonderland, by Lewis Carroll. The cat tends to disappear, leaving only its smile hanging in the air.

Note: “Smiling like a Cheshire cat” refers to anyone with a conspicuous and long-lasting smile.
Idioms and Phrases with grin like a cheshire cat

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.