the.com/cuff link

means A small decorative fastener, usually a pair joined by a post or chain, used to close shirt cuffs that have buttonholes but no buttons.

from Cuff links emerged in the 1600s–1700s as shirt cuffs, once simply tied with ribbon or string, became stiffer and more formal, needing a sturdier closure. The word 'cuff' traces back to a Middle English term for a glove or mitten, later extended to the sleeve-end of a garment. 'Link' comes from Old Norse roots meaning a ring or bend, the same sense used for chain links — fitting, since early cuff fasteners were literally two buttons or studs joined by a small connecting chain, which is still the basic design today.