1. (

• countersink ,

) a hole (usually in wood) with the top part enlarged so that a screw or bolt will fit into it and lie below the surface ;

2. (

• counterbore ,
• countersink ,
• countersink_bit

) a bit for enlarging the upper part of a hole ;

1. (

• set ,
• countersink

) insert (a nail or screw below the surface, as into a countersink) ;