prophylactic
adjective medical specialized uk/ˌprɒf.ɪˈlæk.tɪk/ us/ˌprɑː.fɪˈlæk.tɪk/
预防（性）的
preventing disease
Some dentists are convinced that the addition of fluoride in water is ineffective as a prophylactic treatment. 有些牙医坚信在水中加氟化物不是有效的预防措施。
prophylactic
noun [ C ] uk/ˌprɒf.ɪˈlæk.tɪk/ us/ˌprɑː.fɪˈlæk.tɪk/
medical specialized预防药（剂）
something that is intended to prevent disease
mainly US避孕套，保险套
a condom