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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quan·tum 'kwänt-əm n, pl quan·ta 'kwänt-ə
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 as”] 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.

Look at other dictionaries:

  • quantum — plur. quanta [ k(w)ɑ̃tɔm, k(w)ɑ̃ta ] n. m. • 1624; mot lat. « combien » 1 ♦ (par l angl.) Philos. Quantité déterminée. ♢ Dr., admin. Montant (d une amende, d une pension, d une part). 2 ♦ (1911; all …   Encyclopédie Universelle

  • Quantum — Quan tum, n.; pl. {Quanta}. [L., neuter of quantus how great, how much. See {Quantity},] 1. Quantity; amount. Without authenticating . . . the quantum of the charges. Burke. [1913 Webster] 2. (Math.) A definite portion of a manifoldness, limited… …   The Collaborative International Dictionary of English

  • quantum — (n.) 1610s, one s share or portion, from L. quantum how much, neuter singular of quantus how great (see QUANTITY (Cf. quantity)). Introduced in physics by Max Planck, 1900; reinforced by Einstein, 1905. Quantum theory is from 1912; quantum… …   Etymology dictionary

  • Quantum 2 — Localisation Coordonnées …   Wikipédia en Français

  • Quantum — (von lateinisch für „wie viel“, „wie groß“) ist: ein umgangssprachlicher Begriff mit der Bedeutung eine bestimmte Menge oder eine bestimmte Anzahl eine ehemalige Automobilmarke; siehe Quantum (Automarke) ein US Unternehmen, das… …   Deutsch Wikipedia

  • quantum — index bulk, proportion, quantity, quota Burton s Legal Thesaurus. William C. Burton. 2006 …   Law dictionary

  • quantum — UK US /ˈkwɒntəm/ noun [C, usually singular] FORMAL ► an amount of something: quantum of sth »Earnings depend on the quantum of work done by you. »During this period, the quantum of oil production increased to 16.10 million barrels from 15.84… …   Financial and business terms

  • Quantum — Sn erw. fremd. Erkennbar fremd (16. Jh.) Entlehnung. Neutralform von l. quantus wieviel . Wird aus der Wissenschaftssprache und Kaufmannssprache übernommen und nicht eingedeutscht.    Ebenso nndl. quantum, ne. quantum, nfrz. quantum, nschw.… …   Etymologisches Wörterbuch der deutschen sprache

  • quantum — |quantum| s. m. 1. Quantidade ou soma que não se designa. 2. Quantidade referente a cada um numa repartição. 3. Montante de uma indenização. 4.  [Física] Quantidade mínima de energia que pode ser emitida, propagada ou absorvida. [A teoria dos… …   Dicionário da Língua Portuguesa

  • Quantum — Quantum: Der Ausdruck für »Menge, Anzahl; Anteil; ‹bestimmtes› Maß« wurde im 17. Jh. in der Kaufmannssprache aus lat. quantum, dem Neutrum von lat. quantus »wie groß, wie viel; so groß wie« übernommen. – Dazu: Quantität »Menge, Masse, Anzahl; (in …   Das Herkunftswörterbuch

  • quantum — [kwän′təm] n. pl. quanta [kwän′tə] [L, neut. sing. of quantus, how much: see QUANTITY] 1. quantity, or amount 2. a specified quantity; portion 3. in the quantum theory, a (or the) fixed, elemental unit, as of energy, angular momentum, etc …   English World dictionary

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