The Collaborative International Dictionary of English v.0.48:

Shorten \Short"en\, v. i.
   To become short or shorter; as, the day shortens in northern
   latitudes from June to December; a metallic rod shortens by
   cold.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Shorten \Short"en\, v. t. [imp. & p. p. Shortened ?; p. pr. &
   vb. n. Shortening.] [See Short, a.]
   1. To make short or shorter in measure, extent, or time; as,
      to shorten distance; to shorten a road; to shorten days of
      calamity.
      [1913 Webster]

   2. To reduce or diminish in amount, quantity, or extent; to
      lessen; to abridge; to curtail; to contract; as, to
      shorten work, an allowance of food, etc.
      [1913 Webster]

            Here, where the subject is so fruitful, I am
            shortened by my chain.                --Dryden.
      [1913 Webster]

   3. To make deficient (as to); to deprive; -- with of.
      [1913 Webster]

            Spoiled of his nose, and shortened of his ears.
                                                  --Dryden.
      [1913 Webster]

   4. To make short or friable, as pastry, with butter, lard,
      pot liquor, or the like.
      [1913 Webster]

   To shorten a rope (Naut.), to take in the slack of it.

   To shorten sail (Naut.), to reduce sail by taking it in.
      [1913 Webster]

WordNet (r) 3.0 (2006):

shorten
    v 1: make shorter than originally intended; reduce or retrench
         in length or duration; "He shortened his trip due to
         illness" [ant: lengthen]
    2: reduce in scope while retaining essential elements; "The
       manuscript must be shortened" [syn: abridge, foreshorten,
       abbreviate, shorten, cut, contract, reduce] [ant:
       dilate, elaborate, enlarge, expand, expatiate,
       exposit, expound, flesh out, lucubrate]
    3: make short or shorter; "shorten the skirt"; "shorten the rope
       by a few inches"
    4: become short or shorter; "In winter, the days shorten" [ant:
       lengthen]
    5: edit by omitting or modifying parts considered indelicate;
       "bowdlerize a novel" [syn: bowdlerize, bowdlerise,
       expurgate, castrate, shorten]

The Free On-line Dictionary of Computing (19 January 2023):

Shorten

    A form of lossless audio
   compression.

   [Details?]

   (2001-12-17)