Definitions of drain:

• noun:   emptying accomplished by draining
• noun:   a gradual depletion of energy or resources

  Example: "A drain on resources"

• noun:   a pipe through which liquid is carried away
• noun:   tube inserted into a body cavity (as during surgery) to remove unwanted material
• verb:   flow off gradually

  Example: "The rain water drains into this big vat"

• verb:   empty of liquid; drain the liquid from

  Example: "We drained the oil tank"

• verb:   deplete of resources

  Example: "The exercise class drains me of energy"

• verb:   make weak

  Example: "Life in the camp drained him"

• name:  A surname (rare: 1 in 50000 families; popularity rank in the U.S.: #5166)