Both fawn and fetus derive from Latin fetus, “the bearing, bringing forth, or hatching of young.”
The noun fawn, meaning “young deer,” came into English use in the middle of the 14th century, by way of Anglo-French from the Old French word faon, “young animal.” At first, fawn could refer to the young of any animal, but from the 15th century was applied chiefly to the young of deer. The use of fawn to describe a color originated in the 19th century.
The noun fetus to mean “the young while in the womb or egg,” came into English use in the late 14th century. It could also be used to refer to “young” of plants, such as the fruit or a new shoot of growth.
The verb to fawn, meaning “to show delight or fondness like a dog” comes from a different source. Old English had the adjective faegen, meaning “glad.” The OE verb faegnian meant “to rejoice, be glad, exult.” A dog is said to fawn over its master. In a dog, that’s considered a good thing. Applied to a human being, to fawn means” to grovel, to act slavishly, to show excessive and inappropriate homage to someone or something.” This use of fawn is in frequent use on the web:
‘American Idol’ Fans Fawn Over Adam Lambert At L.A. Tour Stop
Let’s stop fawning over the ‘artists’ who produce rubbish like ‘Antichrist’
Bill O’Reilly fawns over anti-Semitic Islamic supremacist Ahmed Rehab of Hamas-linked CAIR
Gaggle of women fawn over newly single Prince Harry at Polo Classic on Governors Island