Noun counterbore has 1 sense

1. counterbore, countersink, countersink bit - a bit for enlarging the upper part of a hole
   --₁ is a kind of bit
   

counterbore

Noun:

1. A cylindrical flat-bottomed hole made at the top of an existing hole to allow the head of a bolt, screw, or rivet to sit below or level with the surface.

Example sentence: The mechanic used a counterbore to create space for the bolt head in the metal plate.

2. A tool used for creating a counterbore.

Example sentence: I need to purchase a set of counterbores to accurately prepare the holes for the screws.

Verb:

1. To create a counterbore in a hole.

Example sentence: The carpenter counterbored the edges of the wooden board to precisely attach it to the frame.

2. To hollow out beneath the usual level to form a cavity.

Example sentence: The river had counterbored the soil, creating a small recess.

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• Counterbore tools
• Counterbore drill bits
• Counterbore sets