What does excitability mean?
Excitability is the quality of being readily excited or stimulated, and it operates on two distinct levels. In everyday language, it describes a temperament prone to enthusiasm, agitation, or heightened emotional response — the excitable child who cannot sit still before a birthday party exhibits excitability. In science, the word takes on a precise technical meaning: excitability is the fundamental property of nerve and muscle cells that allows them to respond to a stimulus and transmit an electrical signal. Without membrane excitability, neurons could not fire and muscles could not contract, making it one of the most essential concepts in physiology and neuroscience. The connotation depends on context — mildly pejorative when applied to an volatile personality, entirely neutral as a laboratory term. Derived from the Latin 'excitare', meaning to call out or rouse, the word entered English in the seventeenth century and remains valuable precisely because it bridges ordinary emotional description and rigorous biological science.
nounThe quality of being easily excited or stimulated, whether emotionally or physiologically; the capacity of a cell or tissue (especially nerve or muscle) to respond to a stimulus.
- A tendency to become easily excited, agitated, or enthusiastic (of temperament).
- In physiology: the capacity of a nerve, muscle, or other cell to respond to stimulation.
"The puppy's excitability made it difficult to keep him calm around guests."
"Her natural excitability made her a lively but sometimes exhausting companion."
"Caffeine increases the excitability of neurons throughout the central nervous system."
Rarely pluralized; the singular is almost always used even when referring to multiple instances or types, e.g. 'differences in excitability'.
"Researchers compared the excitabilities of different neuronal populations."
In physiology, 'excitability' isn't a mood — it's the defining property of every neuron and muscle fiber in your body: without it, you couldn't think, move, or feel.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of excitability
Excitability derives from the Latin verb 'excitare', meaning to rouse or call out, formed from 'ex-' (out) plus 'citare' (to summon), itself a frequentative of 'ciere' (to stir). The word entered English via the adjective 'excitable' in the early modern period, likely in the early-to-mid 17th century. It shares its Latin root with words such as 'cite', 'incite', and 'resuscitate'. Its specialized physiological sense developed alongside 18th- and 19th-century studies of nerve and muscle response.
Related word forms
How excitability is actually used
Neutral in tone overall. In everyday use it often describes temperament, sometimes implying over-sensitivity or volatility. In scientific contexts (neuroscience, physiology), it is a precise technical term for the ability of cells to generate action potentials in response to stimuli.
Easily confused with excitability
Irritability refers to a tendency toward anger or annoyance (or in physiology, responsiveness to stimuli), whereas excitability refers to being easily excited or aroused by stimuli, often with positive or neutral energy.