1. [n]  a succession of notes forming a distinctive sequence; "she was humming an air from Beethoven"
2. [v]  of musical instruments; "My piano needs to be tuned"
3. [v]  adjust for functioning; "tune the engine"

1. \Tune\, n. [A variant of tone.]
   1. A sound; a note; a tone. ``The tune of your voices.''
      --Shak.
   2. (Mus.)
      (a) A rhythmical, melodious, symmetrical series of tones
          for one voice or instrument, or for any number of
          voices or instruments in unison, or two or more such
          series forming parts in harmony; a melody; an air; as,
          a merry tune; a mournful tune; a slow tune; a psalm
          tune. See {Air}.
      (b) The state of giving the proper, sound or sounds; just
          intonation; harmonious accordance; pitch of the voice
          or an instrument; adjustment of the parts of an
          instrument so as to harmonize with itself or with
          others; as, the piano, or the organ, is not in tune.
                Like sweet bells jangled, out of tune and harsh.
                                                  --Shak.
   3. Order; harmony; concord; fit disposition, temper, or
      humor; right mood.
            A child will learn three times as much when he is in
            tune, as when he . . . is dragged unwillingly to
            [his task].                           --Locke.
   

2. \Tune\, v. t. [imp. & p. p. {Tuned}; p. pr. & vb. n.
   {Tuning}.]
   1. To put into a state adapted to produce the proper sounds;
      to harmonize, to cause to be in tune; to correct the tone
      of; as, to tune a piano or a violin. `` Tune your harps.''
      --Dryden.
   2. To give tone to; to attune; to adapt in style of music; to
      make harmonious.
            For now to sorrow must I tune my song. --Milton.
   3. To sing with melody or harmony.
            Fountains, and ye, that warble, as ye flow,
            Melodious murmurs, warbling tune his praise.
                                                  --Milton.
   4. To put into a proper state or disposition. --Shak.
   

3. \Tune\, v. i.
   1. To form one sound to another; to form accordant musical
      sounds.
            Whilst tuning to the water's fall, The small birds
            sang to her.                          --Drayton.
   2. To utter inarticulate harmony with the voice; to sing
      without pronouncing words; to hum. [R.]
   

(From musical, possibly via automotive, usage) To optimise a program or system for a particular environment, especially by adjusting numerical parameters designed as hooks for tuning, e.g. by changing "#define" lines in C. One may "tune for time" (fastest execution), "tune for space" (least memory use), or "tune for configuration" (most efficient use of hardware).

See bum, hot spot, hand-hacking.

[Jargon File]