counterbore counterborder • counterboycott · · · Info · Definitions · Synonyms · Characters · · counterbore · · Text Latin · · Script 11 · · Length Definitions · · · (noun) a bit for enlarging the upper part of a hole. Synonyms: countersink, countersink bit. · · Noun Definition 1 Synonyms · · · countersink · · Synonym 1 countersink bit · · Synonym 2 Characters · · b latin small letter b U+0062 c latin small letter c U+0063 e latin small letter e U+0065 n latin small letter n U+006E o latin small letter o U+006F r latin small letter r U+0072 t latin small letter t U+0074 u latin small letter u U+0075