During the Qing dynasty (1644-1912), men were required to wear a queue (辫子), a long braid at the back of the head. Cutting it off became a symbol of revolution and modernity.
usage
Almost always used with the suffix 子 as 辫子 (biànzi). The bare character 辫 appears mainly in literary or formal contexts.
辛 on the right is the indexing radical, mirroring the left. Its repetition with 纟 between forms a balanced left-middle-right structure - the two 辛 binding the thread on either side, just as a braid weaves strands under counter-tension.
辛 on the left, originally a knife for tattooing slaves. Two flanking 辛 around a central thread evoke binding under tension - the tight twisting needed to lock hair into a queue. Same shape on right, mirrored composition.
纟 is the silk radical 糸 in left-side form, planted in the middle column. It supplies the actual semantic core - strands woven together. A braid is fundamentally threads being plied, and 纟 makes that plain.