D defs.my
Entry 1 sense Webster, 1913

Headwater

/(-wā`)/ · Head·wa·ter · IPA /hˈɛdwˌɔtər/
01 n. The source and upper part of a stream; -- commonly used in the plural; as, the headwaters of the Missouri.
  1. 1.
    The source and upper part of a stream; -- commonly used in the plural; as, the headwaters of the Missouri.