Brad

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late Middle English: from Old Norse broddr ‘spike’.

wiktionary

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Late Middle English brad, variant of brod(d), from Old Norse broddr(“spike, shaft”), from Proto-Germanic *bruzdaz (compare Old English brord, Old High German brort), from Proto-Indo-European *bʰrusdʰos (compare Welsh brath(“sting, prick”), Albanian bredh(“fir-tree”), Lithuanian bruzdùklis(“bridle”), Czech brzda(“brake”).

etymonline

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brad (n.)

"small flat nail having instead of a head a slight projection on one side," late 13c., brod, from Old Norse broddr "spike, point, arrow," from Proto-Germanic *brozda- (source also of Old English brord "point, prick, blade of grass," Old High German brort "point, edge, crown"), from PIE *bhrs-dh-, from root *bhars- "projectile, point, bristle" (see bristle (n.)).