reservoir
noun
[ ˈrɛzəvwɑː ]
• a large natural or artificial lake used as a source of water supply.
• "the more water we use, the more land has to be flooded for reservoirs"
• a population, tissue, etc. which is chronically infested with the causative agent of a disease and can act as a source of further infection.
• "there is a vast reservoir of herpes infection in the community"
Origin:
mid 17th century: from French réservoir, from réserver ‘to reserve, keep’.
