That’s not a word?

I was revising a novella this morning when a red squiggly line caught my eye.  Typos are the norm for me—she becomes He, that becomes hat and so forth.  But as I honed in with my less than keen sight, I nearly stained my paints with feces.

Frowned.

How the @^#$^^@$@E&%&$##@#!!! is frowned not a word?  It’s something I’ve used my whole life, a word I’ve heard others use my whole life.  A word i’m pretty sure I’ve read countless times.  I right click.

“Suggestion:  Fronde.”

Seriously?  What the hell is a fronde?  Some strange past participle of frown, maybe?  (Well, according to Google, Fronde was a series of French Civil Wars.)  Scrivener, and by association, my Mac, are joining causes to suggest “He had a series of French Civil Wars.”  How he could have had multiple internal strifes that resulted in both sides rolling over and hoisting the white flag each time is beyond me.

Anyway—again, turning to Google—’frowned’ is indeed a word (Webster and Priceton both concur most agreeably).

So my question:  when was the last time you came across a word that your word processor claimed didn’t exist?