force created by the action of the earth (gravity) on an object.

Merriam-Webster Online Dictionary
weight (noun)
a) the amount that a thing - weighs
b) (1) the standard or established amount that a thing should - weigh
(2) one of the classes into which contestants in a sports event are divided according to body weight
(3) poundage required to be carried by a horse in a handicap race
a) a quantity or thing a fixed and usually specified amount - weighing
b) a heavy object (as a metal ball) thrown, put, or lifted as an athletic exercise or contest
a) a unit of weight or mass - see metric system table
b) a piece of material (as metal) of known specified weight for use in weighing articles
c) a system of related units of weight
a) something heavy - load
b) a heavy object to hold or press something down or to counterbalance
a) - burden pressure the weight of their responsibilities
b) the quality or state of being ponderous
c) - corpulence
a) relative heaviness - mass
b) the force with which a body is attracted toward the earth or a celestial body by gravitation and which is equal to the product of the mass and the local gravitational acceleration
a) the relative importance or authority accorded something - the weight of her opinions
b) measurable influence especially on others - throwing his weight behind the proposal
overpowering force
the quality (as lightness) that makes a fabric or garment suitable for a particular use or season - often used in combination summer-weight
a numerical coefficient assigned to an item to express its relative importance in a frequency distribution
the degree of thickness of the strokes of a type character importance, influence
weight (verb)
transitive verb
to oppress with a burden - weighted down with cares
a) to load or make heavy with or as if with a weight
b) to increase in heaviness by adding an ingredient
a) - weigh
b) to feel the weight of - heft
to assign a statistical weight to
to cause to incline in a particular direction by manipulation - the tax structure … which was weighted so heavily in favor of the upper classes A. S. Link
to shift the burden of weight upon - weight the inside ski
weight (Wikipedia)
A spring scale measures the weight of an object.
Common symbols
SI unitnewton (N)
Other units
pound-force (lbf)
In SI base unitskg⋅m⋅s−2
Derivations from
other quantities

In science and engineering, the weight of an object is related to the amount of force acting on the object, either due to gravity or to a reaction force that holds it in place.

Some standard textbooks define weight as a vector quantity, the gravitational force acting on the object. Others define weight as a scalar quantity, the magnitude of the gravitational force. Others define it as the magnitude of the reaction force exerted on a body by mechanisms that keep it in place: the weight is the quantity that is measured by, for example, a spring scale. Thus, in a state of free fall, the weight would be zero. In this sense of weight, terrestrial objects can be weightless: ignoring air resistance, the famous apple falling from the tree, on its way to meet the ground near Isaac Newton, would be weightless.

The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton. For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, and about one-sixth as much on the Moon. Although weight and mass are scientifically distinct quantities, the terms are often confused with each other in everyday use (i.e. comparing and converting force weight in pounds to mass in kilograms and vice versa).

Further complications in elucidating the various concepts of weight have to do with the theory of relativity according to which gravity is modelled as a consequence of the curvature of spacetime. In the teaching community, a considerable debate has existed for over half a century on how to define weight for their students. The current situation is that a multiple set of concepts co-exist and find use in their various contexts.

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