'headwaters' originates from English, specifically the compound of 'head' and 'water', where 'head' meant 'chief, source' and 'water' meant 'stream or body of water'.

'head' comes from Old English 'heafod' and 'water' comes from Old English 'wæter'; these elements combined in Modern English to form the compound 'headwater' and its plural 'headwaters'.

Initially it meant 'the uppermost source(s) of a river', and over time it has remained in use with the current meaning of 'the source(s) or upper tributaries of a river'.