Random internet Native American etymology, including the likely derivation of the name Kemosabe from The Lone Ranger:
https://web.archive.org/web/20160303171525/https://spot.colorado.edu/~koontz/faq/etymology.htm
(Yeah, the show was a product of its time.)
The word slut has more or less always meant dirty, but only recently meant dirrrty.
Chaucer refers to a man as "sluttish" meaning sloppy. Around same time or a bit later it was used for lower class women generally but specifically messy women. There's an interesting "sl" word thing going on with slob, slut, sloppy, slovenly etc.
While brazenness was part of it, slut only came to be specifically sexual by the 1960s.
OK, here's my fave.
The UK was working on a secret project to build armored vehicles capable of carrying field artillery, but for security reasons they didn't want the name of the project alone to give it away.
Using basically the "homework folder" approach to infosec, they planned to refer to the vehicle as a "water carrier." The commander didn't like having the initials be "W.C.," so they came up with a synonym.
Tank.
The word man originally was gender-neutral. Wer was used for male-gendered men and Wif for female. Wif persisted as "wife" and wifman->woman. The wer was dropped in the 10th century or so and man just came to take over.
Which is fun because that wer is the same as werewolf, so there also used to be weremen
Stephen Hoffman
Connor Moran