/bal'euh strair"ee euh/ , n. , pl. balistrariae /-euh strair"ee ee'/ .
(in a medieval fortification) an opening, usually in the form of a cross, through which a crossbow could be fired.
[ 1835-45; bal ( l ) istrarius, L ballistarius pertaining to a BALLISTA (in ML a crossbow), equiv. to ballist ( a ) + -arius -ARY ]