countersink

• ⇰ To chamfer or form a depression around the top of (a hole in wood, metal, etc.) for the reception of the head of a screw or bolt below the surface, either wholly or in part; <as>as, to <ex>countersink</ex> a hole for a screw</as>.
• ⇰ To cause to sink even with or below the surface; <as>as, to <ex>countersink</ex> a screw or bolt into woodwork</as>.

• ⇰ An enlargement of the upper part of a hole, forming a cavity or depression for receiving the head of a screw or bolt.
• ⇰ A drill or cutting tool for countersinking holes.