The Collaborative International Dictionary of English v.0.48:

Appel \Ap`pel"\, n. [F., prop., a call. See Appeal, n.]
   (Fencing)
   A tap or stamp of the foot as a warning of intent to attack;
   -- called also attack.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Attack \At*tack"\, v. t. [imp. & p. p. Attacked; p. pr. & vb.
   n. Attacking.] [F. attaquer, orig. another form of attacher
   to attack: cf. It. attacare to fasten, attack. See Attach,
   Tack a small nail.]
   1. To fall upon with force; to assail, as with force and
      arms; to assault. "Attack their lines." --Dryden.
      [1913 Webster]

   2. To assail with unfriendly speech or writing; to begin a
      controversy with; to attempt to overthrow or bring into
      disrepute, by criticism or satire; to censure; as, to
      attack a man, or his opinions, in a pamphlet.
      [1913 Webster]

   3. To set to work upon, as upon a task or problem, or some
      object of labor or investigation.
      [1913 Webster]

   4. To begin to affect; to begin to act upon, injuriously or
      destructively; to begin to decompose or waste.
      [1913 Webster]

            On the fourth of March he was attacked by fever.
                                                  --Macaulay.
      [1913 Webster]

            Hydrofluoric acid . . . attacks the glass. --B.
                                                  Stewart.
      [1913 Webster]

   Syn: To Attack, Assail, Assault, Invade.

   Usage: These words all denote a violent onset; attack being
          the generic term, and the others specific forms of
          attack. To attack is to commence the onset; to assail
          is to make a sudden and violent attack, or to make
          repeated attacks; to assault (literally, to leap upon)
          is to attack physically by a had-to-hand approach or
          by unlawful and insulting violence; to invade is to
          enter by force on what belongs to another. Thus, a
          person may attack by offering violence of any kind; he
          may assail by means of missile weapons; he may assault
          by direct personal violence; a king may invade by
          marching an army into a country. Figuratively, we may
          say, men attack with argument or satire; they assail
          with abuse or reproaches; they may be assaulted by
          severe temptations; the rights of the people may be
          invaded by the encroachments of the crown.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Attack \At*tack"\, v. i.
   To make an onset or attack.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Attack \At*tack"\, n. [Cf. F. attaque.]
   1. The act of attacking, or falling on with force or
      violence; an onset; an assault; -- opposed to defense.
      [1913 Webster]

   2. An assault upon one's feelings or reputation with
      unfriendly or bitter words.
      [1913 Webster]

   3. A setting to work upon some task, etc.
      [1913 Webster]

   4. An access of disease; a fit of sickness.
      [1913 Webster]

   5. The beginning of corrosive, decomposing, or destructive
      action, by a chemical agent.
      [1913 Webster]

WordNet (r) 3.0 (2006):

attack
    n 1: (military) an offensive against an enemy (using weapons);
         "the attack began at dawn" [syn: attack, onslaught,
         onset, onrush]
    2: an offensive move in a sport or game; "they won the game with
       a 10-hit attack in the 9th inning"
    3: intense adverse criticism; "Clinton directed his fire at the
       Republican Party"; "the government has come under attack";
       "don't give me any flak" [syn: fire, attack, flak,
       flack, blast]
    4: ideas or actions intended to deal with a problem or
       situation; "his approach to every problem is to draw up a
       list of pros and cons"; "an attack on inflation"; "his plan
       of attack was misguided" [syn: approach, attack, plan of
       attack]
    5: the act of attacking; "attacks on women increased last year";
       "they made an attempt on his life" [syn: attack, attempt]
    6: a decisive manner of beginning a musical tone or phrase [syn:
       attack, tone-beginning]
    7: a sudden occurrence of an uncontrollable condition; "an
       attack of diarrhea"
    8: the onset of a corrosive or destructive process (as by a
       chemical agent); "the film was sensitive to attack by acids";
       "open to attack by the elements"
    9: strong criticism; "he published an unexpected attack on my
       work"
    v 1: launch an attack or assault on; begin hostilities or start
         warfare with; "Hitler attacked Poland on September 1, 1939
         and started World War II"; "Serbian forces assailed Bosnian
         towns all week" [syn: attack, assail] [ant: defend]
    2: attack in speech or writing; "The editors of the left-leaning
       paper attacked the new House Speaker" [syn: attack,
       round, assail, lash out, snipe, assault]
    3: take the initiative and go on the offensive; "The Serbs
       attacked the village at night"; "The visiting team started to
       attack" [syn: attack, aggress]
    4: attack someone physically or emotionally; "The mugger
       assaulted the woman"; "Nightmares assailed him regularly"
       [syn: assail, assault, set on, attack]
    5: set to work upon; turn one's energies vigorously to a task;
       "I attacked the problem as soon as I got out of bed"
    6: begin to injure; "The cancer cells are attacking his liver";
       "Rust is attacking the metal"