Vinaigrette

A salad dressing emulsion of oil and an acid (usually vinegar or citrus), seasoned and often mustard-stabilized.

What it means in a kitchen

Classic French ratio: three parts oil to one part vinegar, plus salt, plus a small amount of mustard or shallot to help the emulsion hold. Whisking introduces air and breaks the oil into droplets fine enough to coat a leaf evenly.