There I was, tippity-tapping away on my story, eyes (surely) intense as I put my poor heroine into a terrible situation. Knife at her throat, blade glinting in the lantern light. But that isn’t the villainy–the villainy is in the news he imparts. News that sets her reeling, that makes her spinning world grind to a halt. When the hero rushes up and sees her empty eyes and non-responsiveness, he thinks, “Oh no, she’s in sho—” Wait a minute.
Could she be in shock in 1779? Growl, grumble, away from the story I go to the awesome www.etymonline.com. Where I discover that no, she could not have been (in so many words). BUT– 
Shock. This word entered English round about 1560 and was a military term for a violent attack. In the 1690s the word was used to mean “offend, displease.” So you could shock someone then–but it wasn’t until 1705 that it took on the noun side of that and broadened to mean “a sudden, disturbing impression upon the mind.” 
So things could shock us mentally in 1690, and we’d feel the shock of it in 1705, bwhich is what I needed for my particular story–my heroine could be shocked, just not in shock. That didn’t come about until 1804. Though interestingly, an electric shock dates from almost exactly the same time as the mental shock.
Shocking!