Q]
From Thomas Casey: Why do we call the
eggplant by that name?
[A] This curious comestible (actually a fruit, but eaten as a vegetable) probably has more names in varieties of the English language than any other. That’s because it has been cultivated for a very long time and it has been widely transmitted across the world from its heartland in eastern and southern Asia (the Arabs introduced it to Spain from India as early as the eighth century AD, and the Persians took it to Africa).
The name of
eggplant was given it by Europeans in the middle of the eighteenth century because the variety they knew had fruits that were the shape and size of goose eggs. That variety also had fruits that are a whitish or yellowish colour rather than the wine purple that is more familiar to us nowadays. So the sort they knew really did look as though it had fruits like eggs.
In Britain, it is usually called an
aubergine, a name which was borrowed through French and Catalan from its Arabic name
al-badinjan. That word had reached Arabic through Persian from the Sanskrit
vatimgana, which indicates how long it has been cultivated in India. In India, it has in the past been called
brinjal, a word which comes from the same Arabic source as British
aubergine, but filtered through Portuguese (the current term among English speakers in India is either the Hindi
baingan, or
aubergine). Some people in the southern states of the US still know it as
Guinea squash, a name that commemorates its having been brought there from West Africa in the eighteenth century.
Of these names,
eggplant is the easiest to say and remember, but its prosaic descriptiveness lacks the romance and sense of history that is attached to the others.
reference:
http://www.worldwidewords.org/qa/qa-egg1.htm