Definition of "blackwater"

blackwater

noun
usually uncountable, plural blackwaters
1. Water containing loam, tannins, etc., giving it a very dark appearance.
2. Blackwater fever; malaria caused by Plasmodium falciparum.
  Quotations
  She began talking of the way they had died – blackwater, malaria, a neglected appendix.
  1954, Doris Lessing, A Proper Marriage, HarperPerennial, published 1995, page 155
3. Waste from domestic toilets; water containing fecal matter.
  Quotations
  Ms. Conlin failed to report, among other things, that air emissions are regulated and that our industry is exploring new technologies to further reduce emissions; that our ships treat all blackwater; and that advanced wastewater purification systems discharge water cleaner than most municipal water treatment plants.
  2009 March 1, “Letter: Green Cruising Efforts”, in New York Times‎