ˈbaləs noun
( plural ballas )
Etymology: probably from Portuguese balas, plural of bala, literally, ball, bullet, from Italian palla, of Germanic origin; akin to Old High German balla ball — more at ball
: a nearly spherical aggregate of diamond grains having a radial or granular structure and used as an industrial diamond because of a toughness that is due to the lack of throughgoing cleavage planes