Belays is a term used in sailing to refer to the act of securing or fastening a rope to prevent it from moving. Its antonyms are terms that describe the opposite of securing or fastening. These include words such as loosen, untie, release, discharge, detach, and unfasten. Loosen refers to making something less tight or fixed, while untie means to undo a knot or tie. Release involves setting something free or letting it go, while detach means to separate or disengage from something. Finally, unfasten refers to undoing a fastener or opening something that is tightly secured. All these words are antonyms of belays as they describe actions that are opposite in meaning.