catheter
(kath-i-ter)
  1. A tubular instrument to allow passage of fluid from or into a body cavity. It is often used to drain abscesses.
  2. A tube that is inserted through the urethra into the bladder to drain it of retained urine.
  3. A flexible, hollow tube that may be passed into a blood vessel. It is used to take fluids or give medicine or contrast materials.