Emulsion \E*mul"sion\, n. [From L. emulgere, emulsum: cf. F. ['e]mulsion. See Emulge.]

Any liquid preparation of a color and consistency resembling milk; as:
   (a) In pharmacy, an extract of seeds, or a mixture of oil and water united by a mucilaginous substance.
   (b) In photography, a liquid preparation of collodion holding salt of silver, used in the photographic process.

Source: Webster's Revised Unabridged Dictionary (1913)