(n.) the tendency of some plants to have raised or prominent veins and vessels in their leaves
Certain varieties of plants—including salad vegetables, like lettuces and cabbages—often have quite noticeable veins in their leaves. And that quality is known as bullescence.
That being said, this isn’t a word you’ll hear much down your local greengrocer’s. This is really a strictly botanical term, first recorded in the late 1800s in a fairly esoteric Lexicon of Medicine and the Allied Sciences. (Though hopefully this isn’t a word you’ll hear much down your local doctor’s office either.)
Etymologically, as we mentioned on Twitter the root here is a Latin word, bullescere, literally meaning ‘to bubble’—a reference to the raised, swollen appearance of the ‘bubbled’ veins in the leaves. That verb in turn comes from bulla, a Latin word for a bubble, a ball, or some manner of swollen, globular nodule. Bulla is used in medical parlance with that meaning in English too, but via its Latin roots it also has a curious list of etymological cousins.
The Spanish bolero dance (and the style of short-cut jacket) derives from the same root. The characteristic 3/4 dance is said to be based around a courtship, building from slow and tentative movements early on to dramatic full-blown romantic twirls and grasps towards its climax. In that sense, bolero likely comes from the use of bulla to mean a ball, passed from one person to another and back again—or, more figuratively, to the whirling, spinning motion of the dancers.
Bullets too take their name from this root. Originally, a bullet was a cannonball, hence its connection here to a word for a ball or globe-shaped object. And oddly, papal bulls belong in this group as well: the wax that sealed these religious proclamations often formed knob-like protuberances, from which the documents themselves eventually took their name.