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alpha

[al-fuh]
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noun
  1. the first letter of the Greek alphabet (A, α).
  2. the vowel sound represented by this letter.
  3. the first; beginning.
  4. (initial capital letter) Astronomy. used to designate the brightest star in a constellation.
  5. Chemistry. one of two or more isomeric compounds.
  6. the first in a series of related items: frequently used in chemistry and physics.
  7. Chiefly British. a mark or grade corresponding to an A.Compare beta(def 8), gamma(def 9).
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adjective
    1. (of an animal) having the highest rank in a dominance hierarchy: the alpha female of an elephant pack.
    2. being the most dominant, powerful, or assertive person in a particular group.
    See also alpha male.
  1. alphabetical: Put the files in alpha order.
  2. Chemistry. pertaining or linked to the carbon atom closest to a particular group in an organic molecule.
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Origin of alpha

< Latin < Greek álpha < Semitic; cf. aleph
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for alpha

alpha

noun
  1. the first letter in the Greek alphabet (Α, α), a vowel transliterated as a
  2. British the highest grade or mark, as in an examination
  3. (modifier)
    1. involving or relating to helium-4 nucleian alpha particle
    2. relating to one of two or more allotropes or crystal structures of a solidalpha iron
    3. relating to one of two or more isomeric forms of a chemical compound, esp one in which a group is attached to the carbon atom to which the principal group is attached
  4. (modifier) denoting the dominant person or animal in a groupthe alpha male
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Word Origin

via Latin from Greek, of Phoenician origin; related to Hebrew āleph, literally: ox

Alpha

noun
  1. (foll by the genitive case of a specified constellation) usually the brightest star in a constellationAlpha Centauri
  2. communications a code word for the letter a
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for alpha

n.

c.1300, from Latin alpha, from Greek alpha, from Hebrew or Phoenician aleph (see aleph). The Greeks added -a because Greek words cannot end in most consonants. Sense of "beginning of anything" is from late 14c., often paired with omega (last letter in the Greek alphabet) as "the end." Sense of "first in a sequence" is from 1620s. Alpha male was in use by c.1960 among scientists studying animals; applied to humans in society from c.1992.

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Online Etymology Dictionary, © 2010 Douglas Harper

alpha in Medicine

alpha

(ălfə)
n.
  1. The first letter of the Greek alphabet.
  2. The first one in a series; the beginning.
  3. The first position from a designated carbon atom in an organic molecule at which an atom or radical group may be substituted.
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adj.
  1. Characterizing the atom or radical group that is closest to the functional group of atoms in an organic molecule.
  2. Relating to one of two or more closely related substances, as in stereoisomers.
  3. Relating to or characterizing a polypeptide chain that is one of five types of heavy chains present in immunoglobins.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.