noun
or wetting-out agent | ̷ ̷ ̷ ̷| ̷ ̷-
: any of numerous water-soluble or liquid usually synthetic organic substances that promote spreading of a liquid on a surface or penetration into a material especially by their oriented adsorption on the surfaces in such a way that the wetting liquid is no longer repelled and that are used in mixing solids with liquids, in spreading liquids on surfaces, and as penetrants (as in the textile industry or in spraying with insecticides or fungicides) : a surface-active agent having higher wetting power than detergent or other powers