1. drained of electric charge
discharged

e.g. a dead battery
left the lights on and came back to find the battery drained

Synonym: dead

2. emptied or exhausted of (as by drawing off e.g. water or other liquid)

e.g. a drained marsh
a drained tank
a drained and apathetic old man...not caring any longer about anything

3. very tired

Synonym: knackered