'Mad apple' definitions:

Definition of 'mad apple'

noun

Hairy upright herb native to southeastern Asia but widely cultivated for its large glossy edible fruit commonly used as a vegetable [syn: eggplant, aubergine, brinjal, eggplant bush, garden egg, mad apple, Solanum melongena]

noun

Egg-shaped vegetable having a shiny skin typically dark purple but occasionally white or yellow [syn: eggplant, aubergine, mad apple]

From: GCIDE

Mad-apple \Mad"-ap`ple\, Mad apple \Mad" ap`ple\, n.
1. (Bot.) The eggplant bush (Solanum melongena). See Eggplant.
Syn: eggplant, aubergine, brinjal, eggplant bush, garden egg, Solanum melongena. [1913 Webster + WordNet 1.5]
2. The fruit of the eggplant bush, a large egg-shaped vegetable having a shiny skin typically dark purple but occasionally white or yellow.
Syn: eggplant, aubergine. [WordNet 1.5]