NOUN (6)

1. an authority who withdraws permission;

2. an individualist who withdraws from social interaction;

3. a drug addict who is discontinuing the use of narcotics;

4. a contestant who withdraws from competition;

5. a student who withdraws from the educational institution in which he or she was enrolled;

6. a depositor who withdraws funds previously deposited;

The Collaborative International Dictionary of English v.0.48:

Withdrawer \With*draw"er\, n.
   One who withdraws; one who takes back, or retracts.
   [1913 Webster]

WordNet (r) 3.0 (2006):

withdrawer
    n 1: an authority who withdraws permission
    2: an individualist who withdraws from social interaction
    3: a drug addict who is discontinuing the use of narcotics
    4: a contestant who withdraws from competition
    5: a student who withdraws from the educational institution in
       which he or she was enrolled
    6: a depositor who withdraws funds previously deposited