pound-mass

noun

A unit of mass equal to the weight, on earth (subject to standard gravity), of a mass of one avoirdupois pound, equal to about 453.592 grams. Symbol lbm or lbₘ.

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Meanings

nounpound-mass (plural pounds-mass)

plural pounds-mass

  1. A unit of mass equal to the weight, on earth (subject to standard gravity), of a mass of one avoirdupois pound, equal to about 453.592 grams. Symbol lbm or lbₘ.

    On the moon, however the weight of a pound-mass (lb or lbm) is only about one sixth of a pound-force (lbf).

    2000 October 9, Gérard P. Michon, “What is a slug, in the [engineering] weight measurement system?”, in Numericana.com

Origin

From pound + mass, to differentiate from the unit of weight.

Full word history & related roots →
Cite this entry
APA

pound-mass. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/pound-mass

MLA

“pound-mass.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/pound-mass. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “pound-mass,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/pound-mass.

Source: pound-mass on Wiktionary, CC BY-SA 4.0.