WordNet sense 1 (a just detectable amount):

hint, suggestion

WordNet sense 2 (a suggestion of some quality):

ghost, touch

WordNet sense 3 (an indication that something has been present):

shadow, tincture, vestige

WordNet sense 4 (a drawing created by superimposing a semitransparent sheet of paper on the original image and copying on it the lines of the original image):

tracing

WordNet sense 5 (to go back over again):

retrace

WordNet sense 6 (pursue or chase relentlessly):

hound, hunt

WordNet sense 7 (make a mark or lines on a surface):

delineate, describe, draw, line

WordNet sense 8 (follow, discover, or ascertain the course of development of something):

follow

WordNet sense 9 (read with difficulty):

decipher