Spermatocide: Any agent that is destructive to spermatozoa (that is, kills sperm). Nonoxynol-9 is the most commonly encountered spermatocide in the United States. (The nonoxynols, technically speaking, are nonionic surfactant [surface active] mixtures that vary in the number of repeating ethoxy groups.) They are much used as detergents, emulsifiers... Found on http://www.medterms.com/script/main/art.asp?articlekey=10013