1. A device, such as a saw, used to perform or facilitate manual or mechanical work: "Ivan was very excited because he bought a new tool for his tool chest so he could do more home repairs."
2. A machine; such as, a lathe, used to cut and shape machine parts or other objects: "Michael used the new tool to make a carved newel post for the stairway at home."
3. Something regarded as necessary to the carrying out of one's occupation or profession: "Dictionary compilers believe that every word they find and research is a tool of their trade."
4. Something used in the performance of an operation; an instrument: "The surgeon used a different tool for each phase of the operation."
5. In computer science, an application program, often one that creates, manipulates, modifies, or analyzes other programs: "A programming tool or a software development tool is a program or application that software developers use to create, to debug, to maintain, or otherwise to support various programs and applications."

A fine, often starched net of silk, rayon, or nylon, used especially for veils, evening dresses, tutus, or gowns: "The dress Shirley had for the dance included a full tulle skirt that was embroidered with blue flowers."