The Collaborative International Dictionary of English v.0.48:

After-image \Aft"er-im`age\, n.
   The impression of a vivid sensation retained by the retina of
   the eye after the cause has been removed; also extended to
   impressions left of tones, smells, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

afterimage
    n 1: an image (usually a negative image) that persists after
         stimulation has ceased [syn: afterimage,
         aftersensation]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "afterimage":
   afterbirth, afterclap, aftercrop, aftereffect, afterglow,
   aftergrowth, aftermath, afterpain, aftertaste, balance, butt,
   butt end, by-product, candle ends, chaff, debris, detritus, end,
   fag end, filings, fossil, holdover, husks, leavings, leftovers,
   ocular spectrum, odds and ends, offscourings, optical illusion,
   orts, parings, placenta, rags, refuse, relics, remainder, remains,
   remnant, residue, residuum, rest, roach, rubbish, ruins, rump,
   sawdust, scourings, scraps, secundines, shadow, shavings,
   side effect, spectrum, straw, stubble, stump, survival, sweepings,
   trace, track, trail, trick of eyesight, vestige, wake, waste