Toward the head, source, or upper end of something such as a river or mountain valley.
Adverbial form of 'headward,' combining 'head' with '-wards' (a variant suffix meaning in the direction of). This follows the pattern of adverbs like 'towards,' 'backwards,' and 'upwards.'
Both 'headward' and 'headwards' exist as variants, much like 'toward' and 'towards'—English lets speakers choose, and geographers use both when discussing how valleys and rivers evolve upstream.
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