Nimrod
late 16th century: from Hebrew Nimrōḏ, the name of the great-grandson of Noah, known for his skill as a hunter (see Gen. 10:8-9).
wiktionary
In most English-speaking countries, Nimrod is used to denote a hunter or warrior, because the biblicalNimrod is described as "a mighty hunter". In American English, however, the term has acquired a derogatory meaning of "idiot"; there are various hypotheses as to why. Most examples suggest an intermediate form where Nimrod is used deliberately to mock a hunter. Whether this usage was widespread, or how it influenced the final meaning where the hunter connotation is unintended, might be beyond reach.
etymonline
Nimrod
"great hunter," 1712, a reference to the biblical son of Cush, referred to (Genesis x.8-9) as "a mighty hunter before the Lord." In Middle English he was Nembrot (mid-13c.), founder of cities and builder of the tower of Babel (though Genesis does not name him as such). In 16c.-17c. his name was synonymous with "a tyrant." The word came to mean "geek, klutz" by 1983 in teenager slang, for unknown reasons. (Amateur theories include its occasional use in "Bugs Bunny" cartoon episodes featuring rabbit-hunting Elmer Fudd as a foil; its alleged ironic use, among hunters, for a clumsy member of their fraternity; or a stereotype of deer hunters by the non-hunting population in the U.S.)
