discard, cast, shed, slough, scrap, junk mean to get rid of. discard implies the letting go or throwing away of something that has become useless or superfluous though often not intrinsically valueless.
discard old clothes
cast, especially when used with off, away, or out, implies a forceful rejection or repudiation.
cast off her friends
shed and slough imply a throwing off of something both useless and encumbering and often suggest a consequent renewal of vitality or luster.
shed a bad habit
finally sloughed off the depression
scrap and junk imply throwing away or breaking up as worthless in existent form.