What do you call frozen rain that falls as lumps of ice?

Hail, and it is not frozen raindrops. It forms inside a thunderstorm, where violent updraughts carry a particle of ice up into air well below freezing, coat it in a layer of supercooled water that freezes on contact, and then let it fall - to be caught by the next updraught and taken round again. Cut a hailstone in half and you can count the layers like tree rings.

The size a stone reaches is a direct measure of how strong the updraught was, because it can only stay aloft while the rising air can hold its weight. Golf-ball hail implies winds of well over a hundred kilometres an hour going straight up. The heaviest stone reliably recorded, in Bangladesh in 1986, weighed about a kilogram.

Sleet and hail get confused constantly, and the distinction is the season: sleet is small and forms in winter when rain falls through a cold layer near the ground, while hail is a summer phenomenon and needs the towering convection of a thunderstorm. Snow in July is unremarkable at altitude; hail in July is the sky doing something violent.