valley channel; stream course; watercourse in a valley
Refers to the natural channel or course of a stream within a valley, often used in geographical or hiking contexts.
Walking along the valley channel, a small waterfall came into view.
This stream course swells during heavy rain.
Compound of 谷 (tani, 'valley') and 筋 (suji, 'line, course, channel'). The reading たにすじ follows standard rendaku rules.