A cocktail glass is a stemmed glass which has a cone-shaped bowl which is rounded or completely flat on the bottom and placed upon a stem above a flat base. Though they are often mistakenly referred to as martini glasses, they differ from a martini glass in a couple of ways. Cocktail glasses have smaller, more narrow cups/bowls with rounded or flat bottoms, where martinis generally have larger, wider cups/bowls which are fully conical at the bottom.
It is mainly used to serve cocktails. Its form derives from the fact that all cocktails are traditionally served chilled and contain an aromatic element. Thus, the stem allows the drinker to hold the glass without affecting the temperature of the drink, and the wide bowl places the surface of the drink directly under the drinker's nose, ensuring that the aromatic element has the desired effect.
A standard cocktail glass contains 4.5 US fluid ounces (13 cl).