diarrhea, diarrhoia or diarrhoea

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Is it 'diarrhea', 'diarrhoia' or 'diarrhoea'?

In medicine, diarrhea (from the Greek, "diarrhoia" meaning "a flowing through"), also spelled diarrhoea (see ‘Spelling Differences’ below) is characterized by frequent loose or liquid bowel movements.

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Spelling Differences

diarrhea (American)
diarrhoea (British)
diarrhoia (Greek)

Simplification of 'ae' (æ) and 'oe' (œ). Many words are written with 'ae'/'æ' or 'oe'/'œ' in British English, but a single 'e' in American English. Examples (with non-American letter in bold): diarrhoea, anaemia, anaesthesia, caesium, gynaecology, haemophilia, leukaemia, oesophagus, oestrogen, orthopaedic, paediatric.

Words where British usage varies include encyclopaedia, foetus (though the British medical community deems this variant unacceptable for the purposes of journal articles and the like, since the Latin spelling is actually fetus), homoeopathy, mediaeval.

In American usage, aesthetics and archaeology prevail over esthetics and archeology, while oenology is a minor variant of enology. The Encyclopædia Britannica retained the traditional spelling even after relocating to the U.S.

~ for a detailed explanation, go to
http://en.wikipedia.org/wiki/Spelling_differences#Simplification_of_ae_.28.C3.A6.29_and_oe_.28.C5.93.29
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