WordNet sense 1 (an official who can invalidate or nullify):

invalidator, nullifier

WordNet sense 2 (a person who defecates):

defecator, shitter

WordNet sense 3 (a piece of chain mail covering a place unprotected by armor plate):

gusset

WordNet sense 4 (a hamper that holds dirty clothes to be washed or wet clothes to be dried):

clothes hamper, clothes basket, laundry basket