subtractive

from WordNet (r) 3.0 (2006)

subtractive
    adj 1: constituting or involving subtraction; "a subtractive
           correction" [ant: {additive}]

from The Collaborative International Dictionary of English v.0.48

Subtractive \Sub*trac"tive\, a.
   1. Tending, or having power, to subtract.
      [1913 Webster]

   2. (Math.) Having the negative sign, or sign minus.
      [1913 Webster]