Mark, Mass
The mark was originally a unit of weight for gold and silver common throughout western Europe, and was equal to 8 troy ounces (249 g). Variations throughout the Middle Ages were, however, considerable. Read more 
In the physical sciences, weight is the downward force exerted on matter as a result of gravity. An object's weight is equal to its mass multiplied by the magnitude of the gravitational field. The word entered Old English sometime around the 9th century, and meant the quantity measured with a balance. The word "weight" is commonly used synonymously with "mass", though the two concepts are technically quite distinct.
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Mechanics