1. a device or mechanism used to attach, close, or secure something
2. the act or process of attaching or securing something

Examples

• The jacket has a zipper fastening down the front.
• She struggled with the tiny fastening on her necklace.
• The tent requires proper fastening of all guy ropes.
• Check that all fastenings are secure before lifting the box.
• The dress has button fastenings along the back.
• The fastening of the seatbelt is mandatory for safety.
• He examined the metal fastening on the gate.