The Collaborative International Dictionary of English v.0.48:

Decide \De*cide"\, v. t. [imp. & p. p. Decided; p. pr. & vb.
   n. Deciding.] [L. dec[imac]dere; de- + caedere to cut, cut
   off; prob. akin to E. shed, v.: cf. F. d['e]cider. Cf.
   Decision.]
   1. To cut off; to separate. [Obs.]
      [1913 Webster]

            Our seat denies us traffic here;
            The sea, too near, decides us from the rest.
                                                  --Fuller.
      [1913 Webster]

   2. To bring to a termination, as a question, controversy,
      struggle, by giving the victory to one side or party; to
      render judgment concerning; to determine; to settle.
      [1913 Webster]

            So shall thy judgment be; thyself hast decided it.
                                                  --1 Kings xx.
                                                  40.
      [1913 Webster]

            The quarrel toucheth none but us alone;
            Betwixt ourselves let us decide it then. --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Decide \De*cide"\, v. i.
   To determine; to form a definite opinion; to come to a
   conclusion; to give decision; as, the court decided in favor
   of the defendant.
   [1913 Webster]

         Who shall decide, when doctors disagree? --Pope.
   [1913 Webster]

WordNet (r) 3.0 (2006):

decide
    v 1: reach, make, or come to a decision about something; "We
         finally decided after lengthy deliberations" [syn:
         decide, make up one's mind, determine]
    2: bring to an end; settle conclusively; "The case was decided";
       "The judge decided the case in favor of the plaintiff"; "The
       father adjudicated when the sons were quarreling over their
       inheritance" [syn: decide, settle, resolve,
       adjudicate]
    3: cause to decide; "This new development finally decided me!"
    4: influence or determine; "The vote in New Hampshire often
       decides the outcome of the Presidential election"

The Devil's Dictionary (1881-1906):

DECIDE, v.i.  To succumb to the preponderance of one set of influences
over another set.

    A leaf was riven from a tree,
    "I mean to fall to earth," said he.

    The west wind, rising, made him veer.
    "Eastward," said he, "I now shall steer."

    The east wind rose with greater force.
    Said he:  "'Twere wise to change my course."

    With equal power they contend.
    He said:  "My judgment I suspend."

    Down died the winds; the leaf, elate,
    Cried:  "I've decided to fall straight."

    "First thoughts are best?"  That's not the moral;
    Just choose your own and we'll not quarrel.

    Howe'er your choice may chance to fall,
    You'll have no hand in it at all.
                                                                  G.J.