Meaning of COUNTERBORE in English
— counterborer , n.
/kown"teuhr bawr', -bohr'; kown"teuhr bawr", -bohr"/ , n. , v. , counterbored, counterboring .
1. a tool for enlarging a drilled hole for a portion of its length, as to permit sinking a screw head.
2. the portion of the hole so enlarged.
3. to enlarge (a drilled hole) along part of the length of the hole by drilling with a bit having a greater diameter.
[ 1605-15; COUNTER- + BORE 1 ]
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012