Emulsifier

n. agent which promotes the stabilization of an emulsion

An emulsion is a mixture of two immiscible (unblendable) substances. One substance (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include butter and margarine, espresso, mayonnaise, the photo-sensitive side of photographic film, and cutting fluid for metal working. In butter and margarine, a continuous liquid phase surrounds droplets of water (water-in-oil emulsion). Emulsification is the process by which emulsions are prepared.
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Noun
1. a surface-active agent that promotes the formation of an emulsion
(hypernym) wetting agent, wetter, surfactant, surface-active agent
(hyponym) lecithin
(derivation) emulsify

v. emulsify, change into an emulsion

A chemical that aids in suspending one liquid in another. Usually an organic chemical in an aqueous solution.