The Collaborative International Dictionary of English v.0.48:

Nitrophnol \Ni`tro*ph"nol\, n. [Nitro- + phenol.] (Chem.)
   Any one of a series of nitro derivatives of phenol. They are
   yellow oily or crystalline substances and have well-defined
   acid properties, as picric acid.
   [1913 Webster]

WordNet (r) 3.0 (2006):

picric acid
    n 1: a yellow toxic highly explosive strong acid; used in high
         explosives and as a dye and in chemical reactions