The word Idaho – as in the US state – most likely means nothing at all.
It was first proposed as the name of a different state by politician George M. Willing who said it was derived from the Shoshoni for “the sun comes from the mountains” or “gem of the mountains”. But, it transpired he’d made it up and so Congress decided to name the state (then a territory) Colorado instead.
However, the name caught on and some other places took on the moniker: Idaho County in the Oregon Territory and Idaho Springs in Colorado. There was even a steamship called the Idaho that took miners up-river, spreading the popularity of the word.
Eventually, Idaho County became its own territory. It kept its name and became known as Idaho Territory – ultimately becoming the state that we know as Idaho today.
Bonus fact: Chicago means “stink onions”.