noun
1. : the third person to own or sell a used article
2. : a thirdhand source (as of information)
3. : the third player to have the right to bid in bridge : the third player to play to any trick
4.
a. : a workman who helps the backtender at the dry end of a paper machine
b. : one who under the direction of a second hand supervises a section of workers in a textile mill
c. : a factory worker who assists operators or fixers of machines