irritability

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The quality or state of being irritable; testiness or petulance.
2. n. Pathology Abnormal or excessive sensitivity of a body organ or part to a stimulus.
3. n. Physiology The capacity to respond to stimuli.

Century Dictionary and Cyclopedia

1. n. The quality of being irritable; an irritable state or condition of the mind; proneness to mental irritation; irascibility; petulance: as, irritability of temper.
2. n. In physiology, the property of nerve, muscle, or other active tissue of reacting upon stimuli; in muscles, specifically, the property of contracting when stimulated.
3. n. In botany, that endowment of a vegetable organism by virtue of which a motion takes place in it in response to an external stimulus. Such motion may be obvious in a special organ and sudden, as in the sensitive-plant and Venus's fly-trap, or slow, as in the coiling of a tendril; or it may be internal in the protoplasm, of which while living irritability is a fundamental property, and from which, indeed, the outward motion proceeds. “The external stimulus may be mechanical, simply the contact of a foreign hody, or electrical, or chemical; a sudden change from light to darkness, or a variation in the intensity of the illumination, sometimes acts as a stimulus.” (Vines, Physiology of Plants, p. 301.) Irritability is nearly the same as sensitiveness. See sensitive-plant, protoplasm.
4. n. In pathology, morbid responsiveness to stimuli.

Wiktionary

1. n. The state or quality of being irritable; quick excitability; petulance; fretfulness; as, irritability of temper.
2. n. physiology A natural susceptibility, characteristic of all living organisms, tissues, and cells, to the influence of certain stimuli, response being manifested in a variety of ways.
3. n. medicine A condition of morbid excitability of an organ or part of the body; undue susceptibility to the influence of stimuli.

GNU Webster's 1913

1. n. The state or quality of being irritable; quick excitability; petulance; fretfulness.
2. n. (Physiol.) A natural susceptibility, characteristic of all living organisms, tissues, and cells, to the influence of certain stimuli, response being manifested in a variety of ways, -- as that quality in plants by which they exhibit motion under suitable stimulation; esp., the property which living muscle possesses, of responding either to a direct stimulus of its substance, or to the stimulating influence of its nerve fibers, the response being indicated by a change of form, or contraction; contractility.
3. n. (Med.) A condition of morbid excitability of an organ or part of the body; undue susceptibility to the influence of stimuli. See Irritation, n., 3.

WordNet 3.0

1. n. an irritable petulant feeling
2. n. excessive sensitivity of an organ or body part
3. n. a disposition to exhibit uncontrolled anger