What does fatigability mean?
Fatigability is the degree to which someone or something tires easily — in medical terms, an abnormally low threshold for fatigue. The word belongs mainly to clinical and scientific vocabulary, where it serves as a precise, measurable counterpart to the everyday notion of tiredness: rather than describing the state of being exhausted, it describes the tendency to reach that state quickly. Neurologists and physiologists rely on it especially when assessing muscle performance, since abnormal muscle fatigability that worsens over the course of a day can signal disorders such as myasthenia gravis, while general fatigability may point to anemia, thyroid problems, chronic fatigue syndrome, or overtraining. Derived from the Latin verb 'fatigare', meaning to weary or exhaust, the word entered English in the nineteenth century alongside advances in physiology. Though rarely heard outside professional settings, it offers an elegant, exact alternative to vague phrases like 'tires easily'.
nounThe quality or condition of being easily tired; susceptibility to fatigue, especially the tendency of muscles or a person to become exhausted with unusual rapidity under exertion.
- The tendency to become tired easily; heightened susceptibility to fatigue, especially of muscles under exertion (chiefly medical and physiological use).
"The patient's marked fatigability prompted the neurologist to test for myasthenia gravis."
"Muscle fatigability that worsens through the day is a hallmark symptom of myasthenia gravis."
"The recruits' unusual fatigability during training led the physician to check for anemia."
Rarely pluralized; the word is almost always used as an uncountable mass noun, so readers will nearly always encounter the singular form even when referring to multiple patients or muscle groups.
"The study compared fatigabilities across several patient cohorts."
Doctors don't ask whether you're tired — they ask about your fatigability, because how fast you tire can reveal conditions like myasthenia gravis before almost anything else does.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fatigability
Fatigability derives from the Latin verb 'fatigare', meaning to weary, tire, or exhaust, combined with the suffix '-ability' denoting capacity or susceptibility. The root also gave English 'fatigue' and, via the negative prefix 'in-', 'indefatigable', meaning incapable of being wearied. The compound form emerged in English during the nineteenth century as physiology and clinical medicine developed precise terminology for measuring endurance and exhaustion.
Related word forms
How fatigability is actually used
A formal, technical term used almost exclusively in medicine, physiology, and clinical literature rather than everyday conversation. In ordinary speech, speakers say 'tiring easily' or 'wearing out quickly' instead. In clinical contexts it is often a key diagnostic descriptor, particularly in neurology.
Easily confused with fatigability
Fatigue is the state of tiredness itself, whereas fatigability is the tendency or capacity to become tired quickly.