The Collaborative International Dictionary of English v.0.48:

Slapdash \Slap"dash`\, v. t.
   To apply, or apply something to, in a hasty, careless, or
   rough manner; to roughcast; as, to slapdash mortar or paint
   on a wall, or to slapdash a wall. [Colloq.] --Halliwell.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Slapdash \Slap"dash`\, adv. [Slap + dash.]
   1. In a bold, careless manner; at random. [Colloq.]
      [1913 Webster]

   2. With a slap; all at once; slap. [Colloq.] --Prior.
      [1913 Webster]

WordNet (r) 3.0 (2006):

slapdash
    adv 1: in a careless or reckless manner; "the shelves were put
           up slapdash" [syn: slapdash, slam-bang]
    2: directly; "he ran bang into the pole"; "ran slap into her"
       [syn: bang, slap, slapdash, smack, bolt]
    adj 1: marked by great carelessness; "a most haphazard system of
           record keeping"; "slapdash work"; "slipshod spelling";
           "sloppy workmanship" [syn: haphazard, slapdash,
           slipshod, sloppy]