A measure that indicates how heavy something is: Weights are measured in tons, kilograms, or pounds.

The form Janet had to fill out asked for her height and weight

The heaviness (or mass) of a body in a vacuum, or the weight of a body considered apart from all modifying influences, such as the atmosphere:To determine its absolute weight, a body must be weighed in a vacuum or an allowance must be made for buoyancy (tendency or capacity to remain afloat in a liquid or to rise in air or gas).

Out dated or obsolete units of mass, formerly used in pharmacies:

• Twenty grains equal one scruple.
• Three scruples equal one dram.
• Eight drams equal an apothecary's ounce; oz apoth.
• Twelve such ounces equal an apothecary's pound; lb apoth.

There are 7,000 grains in one pound avoirdupois or 0.454 kilograms.

Units and standards for expressing the amount of some quantity, such as length, capacity, or weight.

The science of measurement standards and methods is known as metrology.

Today the chief systems are the English units of measurement and the metric system

The United States is one of the few countries still using the English system. All other major nations have either converted to the metric system or committed themselves to conversion.

The English system is much older and is said to be less practical than the metric system, and in the United States there has been considerable discussion in favor of adopting the metric system as the principal system, however attempts to legislate such a change in the U.S. Congress have failed.

The basic units of the English system, the yard of length and the pound of mass, are now defined in terms of the metric standards, the meter of length and the kilogram of mass.