Slang is so much fun! When used correctly in historical fiction it can add to the feel of the time period. But slang is also slippery. A phrase that “sounds” historical can be a lot more recent that you think. So, unless you like getting tetchy notes from readers, it pays to check your slang. A word as simple as “okay,” for instance, can take you down the rabbit hole of etymological research and confusion. Okay sounds so… modern, right? Well, it depends how you spell it. According to Oxford Dictionary online , the first use of this word (spelled OK) appeared in the 1830s, perhaps originating as an abbreviation of orl korrek t—“a jokey misspelling of 'all correct' which was current in the US in the 1830s.” So, if your fictional setting is firmly planted in late 19th century U.S. (as mine is), OK is okay! But—guess what!— okay is not! It didn’t appear until 1929, according to the Online Etymology Dictionary . Another useful tool for chasing down the time frame of period s...