I find “fatigue” a very vague term, so I don’t use it myself, because I’ve found exact analysis helps find triggers and relief and explain docs & physios better.
For the (A) tiredness part I use
1. dozy, either getting up 4-8x per night or in stints in the day, when my mind is awake, but I may want/need to sleep,
2. drowsy, when both mind & body are tired and
3. numb, in my head, due more to meds like amitriptyline and CBD which I have stopped taking coz of that.
I also separate
4. itchy eyes from tiredness, because sometimes that suggests to me I’m tired altho my body doesn’t (dry eyes), sometimes it does,
part of my tiredness I’ve been realizing/testing the last few weeks is the
5. feverishness-feeling, which I thought was separate, but I now believe is not, because I now nap successfully then, and make my overall sleep more effective
For (B) the missing energy I have
6. quick exhaustibility (energy spurts, I’m an odd one there)
7. then outright exhaustion of the muscles (like you kait I still have my full muscle strength and have had similar discussions)
8. feebleness, dullness, in mind & body,
( C) a deep ‘fatigued’ pain
9. the Big Ache, due to overdoing it (both different to the sore muscles I used to have),
plus D) mentally
10. the inner fatigue, which I think a lot of people have, esp. with ME/CFS, may be sort of listless and have to do with depressiveness/depression, but I only seldom have. I also guess
11. brain fog belongs in here too.
I think what most people mean with fatigue is my #7 & 9(?)