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.
Contemporary definitions for Cheshire cat
noun

a cat with a broad grin, esp. fictitious

Word Origin

from Lewis Carroll's Alice's Adventures in Wonderland

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.