Stradivarius to refer to instruments made by Antonio Stradivari is probably the closer analog to Fender referring to instruments made / designed by Leo Fender. Jazz and Precision were the model names for two his instruments designs. People probably originally said "Jazz copies" or "Jazz style", but got lazy and they became "generic descriptors" or "proprietary eponyms" in the same manner as Rollerblade, Kleenex etc. I know when I visited Sadowsky and bought my guitar, their staff were very careful to use "S-style" instead of Strat.