1. [n]  the principal field of study of a student at a university; "her major is linguistics"
2. [n]  a commissioned military officer in the United States Army or Air Force or Marines; below lieutenant colonel and above captain
3. [n]  a university student who is studying a particular field as the principal subject; "she is a linguistics major"
4. [adj]  greater in number or size or amount; "a major portion (a majority) of the population"; "Ursa Major"; "a major portion of the winnings"
5. [adj]  greater in scope or effect; "a major contribution"; "a major improvement"; "a major break with tradition"; "a major misunderstanding"
6. [adj]  (law) of full legal age; "major children"
7. [adj]  (music) of a scale or mode; "major scales"; "the key of D major"
8. [adj]  of the field of academic study in which one concentrates or specializes; "his major field was mathematics"
9. [adj]  of greater importance or stature or rank; "a major artist"; "a major role"; "major highways"
10. [adj]  of greater seriousness or danger; "a major earthquake"; "a major hurricane"; "a major illness"
11. [v]  have as one's principal field of study; "She is majoring in linguistics"

Major
Lon Nolan's latest assignment carries him to a distant mining planet, where he and his men will stand toe to toe with an enemy arming that has been raiding outlying settlements. Original.

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1. \Ma"jor\, [L. major, compar. of magnus great: cf. F.
   majeur. Cf. {Master}, {Mayor}, {Magnitude}, {More}, a.]
   1. Greater in number, quantity, or extent; as, the major part
      of the assembly; the major part of the revenue; the major
      part of the territory.
   2. Of greater dignity; more important. --Shak.
   3. Of full legal age. [Obs.]
   4. (Mus.) Greater by a semitone, either in interval or in
      difference of pitch from another tone.
   {Major axis} (Geom.), the greater axis. See {Focus}, n., 2.
   {Major key} (Mus.), a key in which one and two, two and
      three, four and five, five and six and seven, make major
      seconds, and three and four, and seven and eight, make
      minor seconds.
   {Major offense} (Law), an offense of a greater degree which
      contains a lesser offense, as murder and robbery include
      assault.
   {Major premise} (Logic), that premise of a syllogism which
      contains the major term.
   {Major scale} (Mus.), the natural diatonic scale, which has
      semitones between the third and fourth, and seventh and
      fourth, and seventh and eighth degrees; the scale of the
      major mode, of which the third is major. See {Scale}, and
      {Diatonic}.
   {Major second} (Mus.), a second between whose tones is a
      difference in pitch of a step.
   {Major sixth} (Mus.), a sixth of four steps and a half step.
      In major keys the third and sixth from the key tone are
      major. Major keys and intervals, as distinguished from
      minors, are more cheerful.
   {Major term} (Logic), that term of a syllogism which forms
      the predicate of the conclusion.
   {Major third} (Mus.), a third of two steps.
   

2. \Ma"jor\, n. [F. major. See {Major}, a.]
   1. (Mil.) An officer next in rank above a captain and next
      below a lieutenant colonel; the lowest field officer.
   2. (Law) A person of full age.
   3. (Logic) That premise which contains the major term. It its
      the first proposition of a regular syllogism; as: No
      unholy person is qualified for happiness in heaven [the
      major]. Every man in his natural state is unholy [minor].
      Therefore, no man in his natural state is qualified for
      happiness in heaven [conclusion or inference].
   Note: In hypothetical syllogisms, the hypothetical premise is
         called the major.
   4. [LL. See {Major}.] A mayor. [Obs.] --Bacon.