(medical医学)a medicine, device or course of action that prevents disease预防性药物(或器具、措施)
(North American English, formal)a condom(= a thin rubber tube that a man wears over his penis during sex to stop a woman from becoming pregnant or to protect against disease)预防疾病的
Word Originlate 16th cent.: from French prophylactique, from Greek prophulaktikos, from pro ‘before’ + phulassein ‘to guard’.