Cheshire cat

Proper noun

the Cheshire cat (plural Cheshire cats)

1. A fictional cat with a broad fixed grin, made popular by Lewis Carroll's Alice's Adventures in Wonderland (1865).
   • CHESHIRE CAT. He grins like a Cheshire cat; said of any one who shows his teeth and gums in laughing.1788, Francis Grose, A classical dictionary of the vulgar tongue, 2nd corrected and enlarged edition, London
   • “Please would you tell me,” said Alice, a little timidly, for she was not quite sure whether it was good manners for her to speak first, “why your cat grins like that?” “It’s a Cheshire-Cat,” said the Duchess, “and that’s why.”1865, Lewis Carroll, Alice's Adventures in Wonderland
2. (attributive) A technique that involves hiding a class's data behind a pointer, so that the code remains binary-compatible even after future changes to members and functionality.
   • the Cheshire cat idiom
   • the Cheshire cat technique