prolonged

adjective

1. Of long duration: chronic, continuing, lingering, persistent, protracted. See continue/stop/pause.
2. Extending tediously beyond a standard duration: dragging, drawn-out, lengthy, long¹, long-drawn-out, overlong, protracted. See excite/bore/interest, long/short.
3. Having great physical length: elongate, elongated, extended, lengthy, long¹. See long/short.

The adjective has 3 meanings:

Meaning #1: relatively long in duration; tediously protracted
  Synonyms: drawn-out, extended, lengthy, protracted

Meaning #2: drawn out or made longer spatially
  Synonyms: elongated, extended, lengthened

Meaning #3: (of illness) developing slowly or of long duration