Emulsion now means a paint to most ears. The word specifically refers to a suspension of small droplets within another liquid, in such a way that they will not dilute. We use emulsifiers in food to help these immiscible liquids bind together.
But the word has not always meant paint or pesto, in English originally the word meant almonds crushed in water to produce a milky liquid. So the word derives from the Latin mulgeō meaning I milk.
The English ‘milk’ has a similar origin to the Latin. The PIE root h₂melǵ- gives the Proto-Germanic melkaną, source for our milk, as well as Scots melk and German melken. From the PIE root we also get the Sanskrit marjati, meaning to wipe; the Greek αρμέγω (armégo) and Lithuanian melžti, which mean milk.
So next time you have almond milk, you are drinking the original English emulsion.