My first year of living in England, I got sick a few times. Now in my American mind, sick can be a sniffling, sneezing, coughing, aching, stuffy head, fever, Nyquil-swilling cold. Or it can be simply feeling under the weather. Or yes, it can mean a stomach bug.
What I didn’t know then was that in Brit speak, “sick” is vomit. If you tell someone you’ve been sick, it means you’ve literally just vomited (and that’s a graphic detail you probably wouldn’t readily volunteer in the same easy breezy way that you might tell someone you’re under the weather). Sick has very little to do with any kind of non-projectile spewing activity. “Ill” on the other hand is the umbrella Brit term for what we Americans would call “sick.”
And don’t even get me started on the reason Brits drop the “the” when speaking about the hospital. (“He’s been to hospital.” “She’s gone to hospital.” etc.) I still have no idea. If anyone does, please share!