amidol

from The Collaborative International Dictionary of English v.0.48

Amidol \Am"i*dol\, n. [Amide + -ol as in alcohol.] (Photog. &
   Chem.)
   A salt of a diamino phenol, {C6H3(OH)(NH2)2}, used as a
   developer.
   [Webster 1913 Suppl.]