Source : Webster's Revised Unabridged Dictionary (1913)

Disinfectant \Dis`in*fect"ant\, n.
   That which disinfects; an agent for removing the causes of
   infection, as chlorine.

Source : WordNet®

disinfectant
     adj : preventing infection by inhibiting the growth or action of
           microorganisms [syn: {bactericidal}, {germicidal}]
     n : an agent (as heat or radiation or a chemical) that destroys
         microorganisms that might carry disease [syn: {germicide},
          {antimicrobic}, {antimicrobial}]