Definition
A hand tool with a hardened steel body and a sharply pointed tip, used to make a small indentation (a 'pock mark') in metal. The indent serves as a starting guide so a drill bit will not wander when it first contacts the surface, and is also used to mark parts for identification or alignment.
Plain English
A pointed metal tool you tap with a hammer to make a tiny dent in a piece of metal. That dent gives a drill bit a place to bite into so it doesn't slip across the surface when you start drilling.
Context Anchor
Seen in aircraft maintenance, especially when laying out and drilling holes in sheet metal, brackets, panels, or repair parts.
Derivation
From 'center' (the middle point you want to mark) and 'punch' (a tool that makes a hole or indent by being struck). The name describes exactly what it does: it punches a center mark.
Why Pilots Care
Precise hole placement prevents drill bits from wandering and damaging thin aluminum aircraft structures.
Intuition Check
A center punch is not used to punch out a hole. It only makes a small starting dent so the drill begins in the right place.
Example Sentence 1
The mechanic used a center punch to mark the spot before drilling out the damaged rivet.
Example Sentence 2
After laying out the new inspection port, he center-punched each location to keep the drill from slipping on the curved fuselage.