Source : Webster's Revised Unabridged Dictionary (1913)

Shammer \Sham"mer\, n.
   One who shams; an impostor. --Johnson.

Source : WordNet®

shammer
     n 1: someone shirking their duty by feigning illness or
          incapacity [syn: {malingerer}, {skulker}]
     2: a person who makes deceitful pretenses [syn: {imposter}, {impostor},
         {pretender}, {fake}, {faker}, {fraud}, {sham}, {pseudo},
        {pseud}, {role player}]