The Collaborative International Dictionary of English v.0.48:

Fixative \Fix"a*tive\, n.
   That which serves to set or fix colors or drawings, as a
   mordant.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fixative
    n 1: a compound (such as ethanol or formaldehyde) that fixes
         tissues and cells for microscopic study
    2: a varnish dissolved in alcohol and sprayed over pictures to
       prevent smudging

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "fixative":
   air brush, ambergris, ambrosia, aromatic, aromatic gum,
   aromatic water, art paper, attar, attar of roses, balance,
   balance rudder, balance wheel, ballast, balm, balm of Gilead,
   balsam, bay oil, bergamot oil, brush, camera lucida,
   camera obscura, canvas, chalk, champaca oil, charcoal, civet,
   counterbalance, counterweight, crayon, drawing paper,
   drawing pencil, drier, easel, essence, essential oil, extract, fin,
   flywheel, governor, ground, gyroscope, hairspring, heliotrope,
   jasmine oil, keel, lavender oil, lay figure, maulstick, medium,
   mordant, musk, myrcia oil, myrrh, paint, paintbrush, palette,
   palette knife, parfum, pastel, pencil, pendulum, perfume,
   perfumery, pigments, rose oil, scent, scratchboard, shock absorber,
   siccative, sketchbook, sketchpad, spatula, spray gun, springs,
   stabilizator, stiffening, stump, tail plane, varnish,
   volatile oil