A rectangular cavity or slot cut into wood or other material to receive a tenon, forming a strong mechanical joint used in traditional woodworking and construction.

A mortise is a rectangular cavity or slot cut into a piece of wood or other material to receive a corresponding projection called a tenon, forming a strong mechanical joint commonly used in traditional woodworking, furniture making, and timber framing for structural connections. This fundamental joinery technique creates exceptionally strong connections that rely on precise fitting and mechanical interlocking rather than just adhesives or fasteners. Mortise joints are essential to traditional craftsmanship and continue to be valued for their strength, durability, and aesthetic appeal in both structural and decorative applications.

The primary purposes include creating strong mechanical connections between wood members, providing structural integrity in timber framing and heavy construction, enabling traditional joinery techniques that have proven durability over centuries, allowing for disassembly and reassembly of structures when needed, distributing loads effectively across joint surfaces, maintaining alignment and preventing movement between connected members, and supporting both functional and decorative woodworking applications.

Types and variations involve through mortises, blind mortises, haunched mortises, and specialty mortise configurations for different applications and structural requirements.

Fun Fact: The mortise and tenon joint is one of the oldest woodworking joints, dating back over 7,000 years! Ancient Egyptian furniture found in tombs still had intact mortise and tenon joints. The joint was so important that medieval guilds closely guarded the secrets of cutting perfect mortises. Interestingly, some Japanese temples built entirely with mortise and tenon joints have stood for over 1,000 years without a single nail!