Eau is a trigraph which occurs in some languages that use the Latin script, such as French and English.
In Modern French, is pronounced pronounced as //o//[1] and often appears at the end of a word. Generally, alternates with in another form of a word, for example, the feminine of chameau (camel) is chamelle. There are three main ways of spelling pronounced as //o//:,, and, out of which is by far the rarest.[2]
In Old French, represented a triphthong, probably pronounced pronounced as /[e̯aɯ̯]/ (or pronounced as /[ə̯aɯ̯]/). This triphthong originated from the Proto-French diphthong pronounced as /[ɛɯ̯]/, which had formed from the sequence of and, where L had vocalized. In the 12th and 13th centuries, both and were used (pronounced as /[i̯aɯ̯]/ was probably a variant pronunciation), but soon became the standard spelling.[3]
In English, only exists in words borrowed from French, and so is pronounced similarly in almost all cases (like in plateau, bureau). Exceptions include beauty and words derived from it, where it is pronounced pronounced as //juː//, bureaucrat where it is pronounced pronounced as //ə//, bureaucracy where it is pronounced pronounced as //ɒ//,[4] and (in some contexts) the proper names Beaulieu and Beauchamp (as pronounced as //juː// and pronounced as //iː//, respectively).[5]
fr:Liliane Sprenger-Charolles
. Linda Siegel . Reading and Spelling Acquisition in French: The Role of Phonological Mediation and Orthographic Factors . Journal of Experimental Child Psychology . February 1998 . 68 . 2 . 134–165 . 10.1006/jecp.1997.2422 . 1 October 2023.