Wiktionary
dispersant
n. (context chemistry English) Any substance that is used to to prevent settling or clumping of particles suspended in a liquid.
Wikipedia
Dispersant
A dispersant or a dispersing agent or a plasticizer or a superplasticizer is either a non-surface active polymer or a surface-active substance added to a suspension, usually a colloid, to improve the separation of particles and to prevent settling or clumping. Dispersants consist normally of one or more surfactants, but may also be gases.
Usage examples of "dispersant".
Among suitable dispersants are acetonitrile, dimethylformamide, propionitrile, and the like.