A liquid used to reduce the surface tension of a cosmetic, lubricant, or another product. Nonoxynol-15 and other nonoxynols are often used to help ingredients dissolve; nonoxynol-9, a related substance, is frequently used as a spermicide.

While nonoxynol-15 is similar to nonoxynol-9, it contains more ethylene oxide and has different chemical properties as a result. Nonoxynol-15 is not used as a spermicide.

It is considered a safe lubricant ingredient.