1. A unit of radiant energy (ε) varying according to the frequency (ν) of the radiation. 2. A certain definite amount. [L. how much]
- q. mottle q. mottle. See entries under under mottle.
- q. rectum Q.R. [L. however much is correct]
- q. satis q.s. [L. however much is enough]
- q. sink in radiologic imaging, the stage at which statistical information reaches its lowest level because of a low photon flux.
- q. sufficiat q.s. [L. however much is enough]
- q.> vis (q.v.) q.v. [L. however much you wish]
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1) one of the very small increments or parcels into which many forms of energy are subdivided <a molecule of rhodopsin in the human eye can cause a response to a single \quantum of light>
2) one of the small molecular packets of a neurotransmitter (as acetylcholine) released into the synaptic cleft in the transmission of a nerve impulse across a synapse
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quan·tum (kwahnґtəm) pl. quanґta [L. “as much asâ€] a unit of energy under the quantum theory. It is hν, in which h is Planck constant, 6.626Ч10−34 joule second, and ν is the frequency of vibration with which the energy is associated. See quantum theory, under theory.Medical dictionary. 2011.