Ja
- Jack
- Mechanical or hydraulic device for lifting heavy equipment off the floor.
- Jack Rafter
- A shortened rafter that joins a hip or valley to the top of a wall plate.
- Jackbolt
- A bolt or screw attached to the baseplate or foundation that is used to move or position the machine that is being moved.
- Jackscrew
- A bolt or screw attached to the baseplate or foundation that is used to move or position the machine that is being moved.
- Japanese Industrial Standards
- Body that produces standards, often abbreviated as JIS.
- Japanese Standards Association
- Body that produces standards.
- Jarno
- A standard taper having 0.600 inch taper per foot used on some machine tools.
- Java
- Object oriented language designed to work on all platforms.
- JavaScript
- An object-oriented scripting language used to enable programmatic access to objects within both the client application and other applications.