The best replacement for source is sink.

The best alternatives to source are rated as following:
★★★★★  sink
★★★★★  resource
★★★  secondary source
★★  1.6
★★  binary
★★  closed source
★★  proprietary software
★  proprietary
★  sole source
★  unreal
★  high twitch
★  udk
★  microsoft
★  dot
★  single source
★  camelbak
★  source
★  sink output
★  sink current
  global offensive
  citation
  commercial software
  reference
  free software
  unreal engine
  createspace
  proprietary operating systems
  cryengine
  open source
  reservoir
  non-point source
  non-point sources
  counter strike
  air source
  sender
  radio shack
  minor source
  competition
  voltage source
  condition zero
  closed source software
  secondary

Your alternative for source is not listed? Suggest!
Speaking about source, one probably shouldn't forget about installous.

Other search terms related to source and their ratings are:
★★★★★ installous
★★ gif
★ radio
You have in mind a companion for source and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of source in all years. Click on graph for more.
source
sink
resource