It is very important that the language in your novel reflects the time and place in which the story is set.
For example, my story is set in Italy. My characters would never “ride shotgun”, a term coined in US in the early 1900s referring to riding alongside the driver with a shotgun to gun bandits.
Do your research! A free tool that I found to be very useful is Ngram Viewer.
You can type any word and see when it started appearing in books. For example…one of my characters was going to say “gazillion” (I write YA) in 1994. Was “gazillion” used back then?
And the answer is…YES! It started trending in 1988 and was quite popular in 1994.
