The Collaborative International Dictionary of English v.0.48:

minor \mi"nor\ (m[imac]"n[~e]r), a. [L., a comparative with no
   positive; akin to AS. min small, G. minder less, OHG.
   minniro, a., min, adv., Icel. minni, a., minnr, adv., Goth.
   minniza, a., mins, adv., Ir. & Gael. min small, tender, L.
   minuere to lessen, Gr. miny`qein, Skr. mi to damage. Cf.
   Minish, Minister, Minus, Minute.]
   [1913 Webster]
   1. Inferior in bulk, degree, importance, etc.; less; smaller;
      of little account; as, minor divisions of a body.
      [1913 Webster]

   2. (Mus.) Less by a semitone in interval or difference of
      pitch; as, a minor third.
      [1913 Webster]

   Asia Minor (Geog.), the Lesser Asia; that part of Asia
      which lies between the Euxine, or Black Sea, on the north,
      and the Mediterranean on the south.

   Minor mode (Mus.), that mode, or scale, in which the third
      and sixth are minor, -- much used for mournful and solemn
      subjects.

   Minor orders (Eccl.), the rank of persons employed in
      ecclesiastical offices who are not in holy orders, as
      doorkeepers, acolytes, etc.

   Minor scale (Mus.) The form of the minor scale is various.
      The strictly correct form has the third and sixth minor,
      with a semitone between the seventh and eighth, which
      involves an augmented second interval, or three semitones,
      between the sixth and seventh, as, 6/F, 7/G[sharp], 8/A.
      But, for melodic purposes, both the sixth and the seventh
      are sometimes made major in the ascending, and minor in
      the descending, scale, thus:
      [1913 Webster]
      [1913 Webster] See Major.

   Minor term of a syllogism (Logic), the subject of the
      conclusion.
      [1913 Webster]

WordNet (r) 3.0 (2006):

minor mode
    n 1: a key based on the minor scale [syn: minor key, minor
         mode]