Mass

MASS /mæs/
nounB1
FormalInformalScientific

A measure of the amount of matter in an object; it is also a measure of an object's resistance to acceleration (inertia).

Unlike weight, which is a force (mass * gravity), mass is an intrinsic property of an object and remains constant regardless of gravity.

The story behind the word. The word "mass" comes from the Latin "massa," meaning "a lump, dough, or heap." This, in turn, came from the Greek "maza," also meaning "barley-cake, lump." It originally referred to a coherent body of matter, a meaning that evolved into its precise scientific definition.

Word relationships

  • bulk: "Bulk" refers to size or volume, which can be related to mass but isn't the same.
  • quantity: "Quantity" is a general term for an amount, while "mass" is a specific physical property.
  • emptiness: Lack of matter.
  • void: An empty space.

Commonly confused with

  • Weight: Mass is the amount of matter; weight is the gravitational force on that mass.

Word family

  • massive (adjective): Large and heavy.
  • massy (adjective): Having mass (less common).

Collocations

  • atomic mass
  • critical mass
  • relative mass
  • center of mass
  • conserve mass

Idioms & expressions

  • a mass of
  • the masses
  • mass appeal

Example sentences

  • "The mass of the planet Jupiter is far greater than that of Earth." Discussing a fundamental property of matter.
  • "Energy equals mass times the speed of light squared." From a famous scientific equation. (Albert Einstein, E=mc²)

Memory hook

Imagine a MASSIVE amount of dough, a huge LUMP of flour and water. Massive Lump

When not to use

Do not confuse "mass" with "weight." An astronaut has the same mass on the moon as on Earth, but their weight is much less.

Fun facts

  • The SI unit for mass is the kilogram (kg).
  • Mass is a fundamental property of matter, and according to Einstein, it is a form of energy.

Related words

Inertia, Momentum, Gravity

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