1. [noun] A conduit allowing liquid to flow out of an otherwise contained volume.
2. [noun] (chiefly UK) An access point or conduit for rainwater that drains directly downstream in a (drainage) basin without going through sewers or water treatment in order to prevent or belay floods.
3. [noun] Something consuming resources and providing nothing in return.
4. [noun] (vulgar) An act of urination.
5. [noun] (electronics) The name of one terminal of a field effect transistor (FET).
6. [verb] (intransitive) To lose liquid.
7. [verb] (intransitive) To flow gradually.
8. [verb] (transitive) (ergative) To cause liquid to flow out of.
9. [verb] (transitive) (ergative) To convert a perennially wet place into a dry one.
10. [verb] (transitive) To deplete of energy or resources.
11. [verb] (transitive) To draw off by degrees; to cause to flow gradually out or off; hence, to exhaust.
12. [verb] (transitive) (obsolete) To filter.
13. [verb] (intransitive) (pinball) To fall off the bottom of the playfield.
14. [noun] Emptying something accomplished by allowing liquid to run out of it.
15. [noun] Tube inserted into a body cavity (as during surgery) to remove unwanted material.
16. [noun] A pipe through which liquid is carried away.
17. [noun] A gradual depletion of energy or resources; 'a drain on resources'; 'a drain of young talent by emigration'.
18. [verb] Flow off gradually; 'The rain water drains into this big vat'.
19. [verb] Deplete of resources; 'The exercise class drains me of energy'.
20. [verb] Empty of liquid; drain the liquid from; 'We drained the oil tank'.
21. [verb] Make weak; 'Life in the camp drained him'.
