Other forms: furrows
A furrow is the long groove a plough cuts in a field. Straight, deep, and one of the oldest marks people make on land.
Ploughing a straight furrow is a real skill and there are competitions for it. The word transfers to faces, since a furrowed brow is one creased with worry, and furrowing your brow is the standard description of concentration. There is a fine idiom about independence, since ploughing your own furrow means going your own way regardless of what others are doing.
Middle English
forow
English, today
furrow
From Middle English forow. From Middle English forow, furgh, from Old English furh, from Proto-West Germanic furh, from Proto-Germanic furhs (compare stq Fuurge, Dutch voor, German Furche, Swedish fåra, Norwegian Bokmål fure), from Proto-Indo-European perḱ- (“to dig”). Compare Welsh rhych (“furrow”), Latin porca (“ridge, balk”), Lithuanian prapar̃šas (“ditch”), Sanskrit पर्शान (“chasm”).
Etymology from Wiktionary, CC BY-SA