The Collaborative International Dictionary of English v.0.48:

Objection \Ob*jec"tion\, n. [L. objectio: cf. F. objection.]
   1. The act of objecting; as, to prevent agreement, or action,
      by objection. --Johnson.
      [1913 Webster]

   2. That which is, or may be, presented in opposition; an
      adverse reason or argument; a reason for objecting;
      obstacle; impediment; as, I have no objection to going;
      unreasonable objections. "Objections against every truth."
      --Tyndale.
      [1913 Webster]

   3. Cause of trouble; sorrow. [Obs. or R.]
      [1913 Webster]

            He remembers the objection that lies in his bosom,
            and he sighs deeply.                  --Jer. Taylor.
      [1913 Webster]

   Syn: Exception; difficulty; doubt; scruple.
        [1913 Webster]

WordNet (r) 3.0 (2006):

objection
    n 1: the act of expressing earnest opposition or protest [syn:
         expostulation, remonstrance, remonstration,
         objection]
    2: the speech act of objecting
    3: the act of protesting; a public (often organized)
       manifestation of dissent [syn: protest, objection,
       dissent]
    4: (law) a procedure whereby a party to a suit says that a
       particular line of questioning or a particular witness or a
       piece of evidence or other matter is improper and should not
       be continued and asks the court to rule on its impropriety or
       illegality