A spermicide is a cream, gel, foam or jelly that kills sperm. People put it inside the vagina before sex so that a woman does not become pregnant. It is a countable noun (a spermicide, two spermicides) but is also used uncountably, the way we treat other substances: "use spermicide with the diaphragm". The word is neutral and medical — you would hear it from a doctor, read it on a package, or see it in a health-education book, not usually in casual chat between friends; friends are more likely to name the actual brand or just say "the cream". It often turns up next to the words condom, diaphragm and cervical cap, because health advice normally tells people to use spermicide together with one of those rather than by itself. That is worth knowing because the word carries that quiet warning with it in real texts.

殺精劑（避孕用的殺精藥膏／凝膠）