The definition of a tool is a device with a specific purpose.(noun)
A hammer, paintbrush, computer and wrench are each an example of a tool.
See tool in Webster's New World College Dictionary
Origin: ME toole < OE tol, akin to ON tol < ? IE base *deu- > taw
See tool in American Heritage Dictionary 4
Origin: Middle English
Origin: , from Old English tōl
Origin: , possibly from Old Norse.
Learn more about tool