The Collaborative International Dictionary of English v.0.48:

Aftertaste \Aft"er*taste`\, n.
   A taste which remains in the mouth after eating or drinking.
   [1913 Webster]

WordNet (r) 3.0 (2006):

aftertaste
    n 1: an afterimage of a taste

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "aftertaste":
   afterbirth, afterclap, aftercrop, aftereffect, afterglow,
   aftergrowth, afterimage, aftermath, afterpain, bitter, by-product,
   flavor, gust, palate, placenta, relish, salt, sapidity, sapor,
   savor, savoriness, secundines, side effect, smack, sour, stomach,
   sweet, tang, taste, tongue, tooth, track, trail, wake