The Collaborative International Dictionary of English v.0.48:

Pall-mall \Pall`-mall"\, n. [OF. palemail, It. pallamagio; palla
   a ball (of German origin, akin to E. ball) + magio hammer,
   fr. L. malleus. See 1st Ball, and Mall a beetle.]
   A game formerly common in England, in which a wooden ball was
   driven with a mallet through an elevated hoop or ring of
   iron. The name was also given to the mallet used, to the
   place where the game was played, and to the street, in
   London, still called Pall Mall. [Written also pail-mail and
   pell-mell.] --Sir K. Digby. --Evelyn.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pell-mell \Pell`-mell"\, n.
   See Pall-mall.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pellmell \Pell`mell"\, adv. [F. p[^e]le-m[^e]le, prob. fr. pelle
   a shovel + m[^e]ler to mix, as when different kinds of grain
   are heaped up and mixed with a shovel. See Pell shovel,
   Medley.]
   In utter confusion; with confused violence. "Men, horses,
   chariots, crowded pellmell." --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pell-mell
    adv 1: in a wild or reckless manner; "dashing harum-scarum all
           over the place"; "running pell-mell up the stairs" [syn:
           harum-scarum, pell-mell]
    adj 1: with undue hurry and confusion; "a helter-skelter kind of
           existence with never a pause"; "a pell-mell dash for the
           train" [syn: helter-skelter, pell-mell]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "pell-mell":
   bedlam, brouhaha, chaos, chaotic, chaotically, commotion, confused,
   confusedly, confusion, disorder, disordered, disorderly,
   disorganized, excitement, feverish, feverishly, hastily, hasty,
   helter-skelter, hubbub, hurried, hurriedly, impetuous, impetuously,
   impulsive, impulsively, incautious, incautiously, mad, melee,
   pandemonium, panicky, precipitate, precipitately, rash, rashly,
   reckless, recklessly, slap-bang, slapdash, spontaneously, tumult,
   tumultuous, turmoil, wild, wildly