Easter egg

Meanings

1. A dyed or decorated egg, traditionally associated with Easter and, in the Western European tradition, sometimes hidden for children to find.
2. A chocolate confection in the shape of an egg, sometimes with chocolates or sweets inside.
3. An undocumented function hidden in a program or video game, typically triggered by a particular input sequence or combination of keystrokes.
4. Any image, feature, or other content that is hidden on a video disc or in a movie, trailer, or poster.

Etymology

From Easter + egg. Cognate with German Low German Ooosterei (“Easter egg”), Middle High German ōsterei ("Easter egg"; > modern German Osterei). So called because eggs would be eaten during Easter to break the fasting during Lent. (No eggs, dairy, meat except fish, lard, or foods containing these ingredients could be eaten during Lent.) The computing sense is from the early 1980s, popularized by the video game Adventure.