"Kroniskt trötthetssyndrom" in Swedish, but only the BPS people refer to it as "KTS", and a few of them sometimes use "CFS" or "CFS/ME".
"Trötthet" in Swedish means "tiredness", so it's even worse than "fatigue"...
"Utmattningssyndrom" or UMS, burnout, (literally 'exhaustion syndrome') is a...