Late Middle English: from Old French faon, based on Latin fetus 'offspring'; compare with fetus.

• faun from Late Middle English:

  In Roman mythology a faun was a lustful rural deity represented as a man with goat's horns, ears, legs, and tail. The word comes from the name of Faunus, a god of flocks and herds, who was associated with wooded places. He had a sister, Fauna, whose name in turn gives us fauna, which since the late 18th century has been used to mean ‘the animals of a particular region or period’. Flora (late 18th century), ‘the plants of a particular region or period’ comes from the name of Flora, an ancient Italian goddess of fertility and flowers, source also of floral (mid 18th century), floret (late 17th century), florid (mid 17th century), and florist (early 17th century). See also flower.

  The identically sounded fawn (Late Middle English) meaning ‘a young deer’ comes from Old French faon and is based on Latin fetus ‘offspring’. The word did not mean ‘a light brown colour’ until much later, in the late 19th century. The verb fawn is earlier, and is a quite different word. In Old English fagnian meant ‘make or be glad’, often used of a dog showing delight by wagging its tail, grovelling, or whining. Fawn was then used to convey the idea of a person giving a servile display of exaggerated flattery or affection, particularly in order to gain favour.

Old English fagnian 'make or be glad', of Germanic origin; related to fain.