Wa"ter*shed` (?), n. [Cf. G. wasserscheide; wasser water + scheide a place where two things separate, fr. scheiden to separate.]
1.
The whole region or extent of country which contributes to the supply of a river or lake.
2.
The line of division between two adjacent rivers or lakes with respect to the flow of water by natural channels into them; the natural boundary of a basin.
© Webster 1913.