French

In Modern French, eau is pronounced /o/ and may or may not be the same phoneme

Phoneme

In a language or dialect, a phoneme is the smallest segmental unit of sound employed to form meaningful contrasts between utterances....

 as the one attached to the letter o.

It is used as an ending for several words, like “berceau” (cradle

Cradle

Cradle may refer to:Mechanical devices:*Bassinet, a small bed, often on rockers, in which babies and small children sleep* Ship cradle, supports a ship that is dry docked...

) or “manteau” (coat

Coat (clothing)

A coat is a long garment worn by both men and women, for warmth or fashion. Coats typically have long sleeves and are open down the front, closing by means of buttons, zippers, hook-and-loop fasteners, toggles, a belt, or a combination of some of these...

), usually being the remnant of a suffix (bercer — to cradle, mante — mantle

Mantle (clothing)

A mantle is a type of loose garment usually worn over indoor clothing to serve the same purpose as an overcoat...

). But this is also a word by itself: eau means water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

.

English

In English

English language

English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

, eau only exists in words imported from French, and so is pronounced likewise in almost all cases. The only exceptions to this are “beauty” and formations of it (excepting plain “beau”) where it is pronounced /juː/, “bureaucrat” where it is pronounced /ə/, and “bureaucracy

Bureaucracy

A bureaucracy is an organization of non-elected officials of a governmental or organization who implement the rules, laws, and functions of their institution, and are occasionally characterized by officialism and red tape.-Weberian bureaucracy:...

” where it is pronounced /ɑ/.