ailing

An ailment.

When you're well enough off so's you don't have to fret about anything but your heft or your diseases you begin to get queer, I suppose. And the queerer the cure for those ailings the bigger the attraction. A place like the Right Livers' Rest was bound to draw freaks, same as molasses draws flies.

Sickly; sick; ill; unwell.

She cared for her ailing brother day in, day out.

Based on the successful Class 59 but with a much more modern engine, what was to become the Class 66 was designed to replace much of the company's elderly and ailing locomotive fleet.