The word ?orange? first entered our English language in the fourteenth century [[as ?orenge? the fruit, and earlier as a surname in the late 13th century]] in reference to the globose citrus fruit of the orange tree (?orange? referring to the tree itself, as in ?groves of oranges,? took another 250 or so years to appear).
The earlier history of the word is a bit of a mess, but roughly, English borrowed it from Old French ?orenge,? [[also in ?pome dorange? and in Medieval Latin ?pomum de orenge?]] which borrowed it from Arabic ?náranj,? which borrowed it from Persian ?nárang,? which borrowed it from Sanskrit ?náranga? orange tree (all foregoing acute accents should really be macrons, and the second ?n? in the Sanskrit word should have a dot over it).
If you're wondering what happened to the initial ?n-,? the probable answer is that it was lost by ?metanalysis,? which, we recall is a change in the division between words, which in English gives rise to ?an adder,? originally ?a nadder.? The original French was probably ?une narenge,? with the definite article absorbing the initial ?n-? of the noun. Spanish, by contrast, also borrowed the Arabic word, but in Spanish it ended up as ?naranja,? since the word didn't undergo metanalysis. The change in French from ?arange? to ?orenge? is thought to be due to the influence of French or 'gold', alluding to the color, or perhaps ?Orange,? a town in southeast France through which oranges were shipped.
taken from
http://www.wordwizard.com/clubhouse/founddiscuss.asp?Num=3650
