(of a person, thing, situation, etc.) Causing irritation, annoyance, or discomfort; bothersome, irksome.
My old car is very nettlesome.
(of a task, problem, etc.) Thorny; difficult to deal with, especially due to being complex or tricky.
The task of proving Fermat’s “last” theorem remains nettlesome.
Be careful what you say to him; he's a nettlesome fellow.
It so chanced that on the second day after my arrival a pack-train came along, guided by a nettlesome old man and a strong, black-haired lass of sixteen or thereabouts. The old man . . . had no sooner slipped the packs from the horses than he began to rail at Hans, who stood looking on. "You damned Dutchmen all be Tories, and worse," he cried.