prophylactic

noun

1. A medicine which preserves or defends against disease; a preventive.
2. (US, specifically)A medicine which preserves or defends against disease; a preventive.

   “It is not clear whether such education is to be directed to homosexuals (for whom prophylactics are not a contraceptive) or to heterosexuals as well (for whom prophylactics are a contraceptive).”

   “Given the widespread use of coitus interruptus and male prophylactics as contraceptive practices in France […]”

   “Some men put the prophylactic on just the tip of the penis: this is a mistake, because the prophylactic will come off.”

3. (figuratively)Any device or mechanism intended to prevent harmful consequences.

   “The securities laws are a prophylactic against stock fraud.”

   “Since tere are increasingly powerful anti-free speech tendencies in the left in general and in the Lesbian and Gay movements in particular in the form of the antiporn movement and other tendencies, I will quote extensively from the second chapter of On Liberty, "On The Liberty Of Thought And Discussion," as a valuable and much needed prophylactic to these trends.”

adj

1. Serving to prevent or protect against an undesired effect, especially disease or pregnancy.