drain vs outflow

drain

verb
  • To flow gradually. 

  • To draw off by degrees; to cause to flow gradually out or off; hence, to exhaust. 

  • To deplete of energy or resources. 

  • To convert a perennially wet place into a dry one. 

  • To fall off the bottom of the playfield. 

  • To cause liquid to flow out of. 

  • To lose liquid. 

noun
  • Something consuming resources and providing nothing in return. 

  • One terminal of a field effect transistor (FET). 

  • 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. 

  • An outhole. 

  • A conduit allowing liquid to flow out of an otherwise contained volume; a plughole (UK) 

  • An act of urination. 

outflow

verb
  • To flow outward. 

noun
  • Any outward movement. 

  • Something that flows out of a sewage treatment plant. 

  • The process of flowing out. 

  • A fluid that flows out. 

  • A stream of gaseous material emanating from an active galactic nucleus. 

  • The part of a system that allows material to flow out. 

How often have the words drain and outflow occurred in a corpus of books? (source: Google Ngram Viewer )