What it means
A very British old-school intensifier you drop in when you want to sound dead serious without going full swear mode. It means absolutely or I really mean it, often in lines like I jolly well won’t or I jolly well will. These days it’s often half playful, half mock-posh, with a bit of fake outrage bubbling under the teacup.
Usage examples
"I jolly well am not covering your Sunday shift, mate. He started the guilt trip, so I grabbed my coat and legged it before he could waffle."
"I jolly well will have the last biscuit, I bought the whole packet after all."
"You can sulk all you like, but you're jolly well coming to your gran's birthday."
"I jolly well did text you back, you just never checked your phone properly."
"She can roll her eyes all she likes, but we're jolly well leaving at eight."
Where it comes from
Jolly has worked as a mild British intensifier since at least the 18th century, first in phrases like jolly good. Jolly well later turned up as a firmer, more stubborn way to add emphasis, especially in set-ups like I jolly well will or I jolly well won't. It carries that polished but defiant British snap.
This expression also appears in
