Geronimo’s birth name was Goyathlay (some sources give Goyakla), “one who yawns.” The reason for his nickname in Spanish are unknown, but it could have been an attempt to pronounce his real name.
It is interesting that the Apache leaders who fought against the Americans at about the same time as the Plains Indians were not called by translations of their Indian names, but rather by either their actual Indian names or European nicknames that were not translations of their Indian names: Geronimo, Mangas Coloradas, Cochise, Nana, Victorio, Juh, Delshay, Nakaidoklini. Neither were the leading figures in the Modoc War in Oregon in 1873: Captain Jack, Hooker Jim, Black Jim, Scarface Charley, Boston Charley, Bogus Charley, John Schonchin, Brancho, and Slolux.
Many animal names we use today are also bastardized versions of the original Native word. For example, “Skunk” is derived from the Algonquian “Sigonku”, meaning “He Who Squirts”. The Europeans had trouble pronouncing it properly.
Same goes for “Moose” - the Cree word for it is “Mooswa” (pronounced MOOSH-wa).
Red Jacket is not a translation of his Indian name, Sagoyewatha. The Red Jacket bit is because he wore a red jacket (go figure). In the 1880s, his body was moved from an Indian cemetary to a more posh location, and outfitted with a spiffy new marker. This has SAGOYEWATHA in big letters, “Red Jacket” is smaller. I guess this surprised me, it seems to indicate that Red Jacket was (correctly) viewed as a nickname, not his actual name, even in the 19th century.
Cornplanter, on the other hand, is a very rough translation of his native name, which I’ve seen written as Kaintwakon, Kantwaka, and probably a million other variations, and means something like “he who is known by that which he plants”. To mix things up even more, Cornplanter also had an English name, John, after his father (who was white).
I have read that it might have been a corruption of Jerome given to him by a priest at a mission in the Apache area, but I don’t remember where I read that.
An aside that’s not quite a hijack: does anybody remember a few years ago when an advocacy group for the mentally ill (I don’t believe it was NAMI or anything that well known, but it may have been) complained about the use of the word “Crazy” in the Crazy Horse Memorial [artist rendering of the memorial upon completion])? They wanted the name reverted to Tashunkewitko or otherwise changed so as not to defame the mentally ill. I thought it was one of the loopier moments among activists (particularly since everybody who sees it is still going to call it Crazy Horse, though to be politically correct they could perhaps have a veterinary psychiatric historian research the horse’s exact illness and perhaps call it “Rapidly-Cycling-Bipolar-Tendencies-as-Described-in-the-DSM-IV-under-221.54* Horse” or whatnot.
*To the more anally inclined: don’t bother looking that particular diagnosis up as I just made the numbers up
It wouldn’t have been a corruption of Jerome, since Geronimo/Jeronimo is just the regular Spanish form of that name.
One story is that when he led a charge against some Mexicans, they began to pray loudly to their patron saint, Jerome (San Geronimo), for help. After his victory in battle Goyathly’s warriors began to call him Geronimo because of their fear-striken cries.