From Websters 1828 Dictionary (link)

Lousy LOUS'Y, a. s as z. [louse.]
1. Swarming with lice; infested with lice.
2. Mean; low; contemptible; as a lousy knave.

From WordNet (r) 2.1 (2005) (link)

  lousy
      adj 1: very bad; "a lousy play"; "it's a stinking world" [syn:
             icky, crappy, lousy, rotten, shitty,
             stinking, stinky]
      2: infested with lice; "burned their lousy clothes"
      3: vile; despicable; "a dirty (or lousy) trick"; "a filthy
         traitor" [syn: dirty, filthy, lousy]

From Merriam-Webster's Collegiate Dictionary, 11th Edition (2003) (link)

  lousy adjective (lousier; -est)
   Date: 14th century 1.  infested with lice 2.
    a.  totally repulsive ; contemptible b.  miserably
    poor or inferior  <got lousy grades> c.  somewhat ill
    <felt lousy after dinner> d.  amply supplied ;
    replete  <lousy with money>
   3. of silk  fuzzy and specked because of splitting of the
   fiber • lousily adverb • lousiness noun
  
  

From Oxford English Reference Dictionary (link)

lousy
adj. (lousier, lousiest)
1 infested with lice.
2 colloq. very bad; disgusting (also as a term of general disparagement).
3 colloq. (often foll. by with) well supplied, teeming (with).
Derivatives:
lousily adv. lousiness n.

From English Explanatory Dictionary (link)

  lousy
  ˈlauzɪ adj. (lousier, lousiest) 1 infested with lice. 2 colloq. very
  bad; disgusting (also as a term of general disparagement). 3 colloq. (often
  foll. by with) well supplied, teeming (with). øølousily adv. lousiness n.
  
  
  

From Webster's Revised Unabridged Dictionary (1913) (link)

  Lousy \Lous"y\, a.
     1. Infested with lice.
  
     2. Mean; contemptible; as, lousy knave. [Vulgar]

From English Explanatory Dictionary (Synonyms) (link)

  lousy
  ˈlauzɪ adj.
  1 awful, terrible, mean, contemptible, low, base, hateful, detestable, despicable, vile,
  wretched, miserable, scurvy, dirty, vicious, Colloq rotten: Telling tales to the teacher was
  a lousy thing to do.
  2 bad, poor, awful, terrible, inferior; low-quality, shoddy, shabby, inferior, miserable,
  second-rate, wretched: We had lousy seats for the theatre last week. The dealer seems to have
  sold you a really lousy car.
  3 pedicular, pediculous, Brit lice-infested, lice-ridden, US louse-infested, louse-ridden:
  Even lice are lousy - they have their own parasites.
  4 lousy with. alive with, overloaded with, swarming with, teeming with, Colloq crawling
  with, knee-deep in: In five minutes the place was lousy with cops.
  
  
  

From Moby Thesaurus II by Grady Ward, 1.0 (link)

  88 Moby Thesaurus words for "lousy":
     abominable, alive with, arrant, atrocious, awful, bad, base,
     beastly, beneath contempt, beset, blameworthy, brutal,
     contemptible, deplorable, despicable, detestable, dire, dirty,
     disgusting, dreadful, egregious, enormous, fetid, filthy, flagrant,
     foul, fulsome, grievous, gross, grubby, hateful, heinous, horrible,
     horrid, infamous, inferior, infested, lamentable, loathsome, low,
     low-quality, mean, miserable, monstrous, nasty, nefarious, noisome,
     notorious, obnoxious, odious, offensive, outrageous, pedicular,
     pediculous, pitiable, pitiful, plagued, poor, rank, ratty, ravaged,
     regrettable, reprehensible, repulsive, rotten, sad, scandalous,
     schlock, scurvy, second-rate, shabby, shameful, shocking, shoddy,
     sordid, squalid, teeming, terrible, too bad, unclean, vicious,
     vile, villainous, woeful, wormy, worst, worthless, wretched