Definition
A clamping device used to hold a workpiece or a cutting tool firmly in place on a lathe, drill press, or similar machine. The chuck grips the item being worked on (or the tool doing the work) so it stays centered and secure while it rotates.
Plain English
A clamp on a workshop machine that holds something tightly so it doesn't move while it spins. Drill chucks hold the drill bit; lathe chucks hold the part being shaped.
Context Anchor
Seen in aircraft maintenance when using drills, lathes, and other shop tools.
Derivation
From an old English word meaning 'a lump' or 'a block.' The name stuck because early chucks were simply blocks of metal shaped to grip a tool. Knowing this helps explain why the word covers a whole family of gripping devices rather than one specific design.
Why Pilots Care
Mechanics and aviation maintenance technicians use chucks routinely. A loose or worn chuck can let a drill bit slip, ruining a part or causing injury. Pilots doing owner-permitted maintenance should know what a chuck is when reading shop manuals or talking with their A&P.
Intuition Check
Do not read chuck here as “throw.” In maintenance, a chuck is a holder that grips something tightly.
Example Sentence 1
The mechanic tightened the drill bit in the chuck before drilling out the damaged rivet.
Example Sentence 2
After tightening the chuck jaws around the shaft, the machinist checked the runout with a dial indicator.