bro·mo·de·oxy·ur·i·dine .brō-mō-.dē-.äk-sē-'yu̇r-ə-.dēn, -dən or 5-bro·mo·de·oxy·ur·i·dine 'fīv-n a mutagenic analog C9H11O5NBr of thymidine that induces chromosomal breakage esp. in heterochromatic regions and has been used to selectively destroy actively dividing cells abbr. BUdR