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- (General American) enPR: härdʹnəs, IPA(key): /ˈhɑɹdnəs/
- (Received Pronunciation) IPA(key): /ˈhɑːdnəs/
Audio (US) (file)
- Hyphenation: hard‧ness
- The quality of being hard.
- c. 1380s, [Geoffrey Chaucer; William Caxton, editor], The Double Sorow of Troylus to Telle Kyng Pryamus Sone of Troye [...] [Troilus and Criseyde], [Westminster]: Explicit per Caxton, published 1482, OCLC 863541017; republished in [William Thynne], editor, The Workes of Geffray Chaucer Newlye Printed, […], book II, [London]: […] [Richard Grafton for] Iohn Reynes […], 1542, OCLC 932884868, folio clxxx, recto:
- For truſteth wel, to longe ydone hardneſſe / Cauſeth diſpyte ful often for diſtreſſe
- For trust this well: Too long maintained hardness / Creates contempt from distress.
- a. 1460, Reginald Pecock, Elsie Vaughan Hitchcock, editor, The Donet, Early English Text Society, published 1921:
- As it is forto se þingis present to þe siȝt, heere þe sown present to þe eeris, touche hardnesse, neischnes, heet, or coold present to þe touche, & so forþe of oþire.
- As it is to see things present to the sight, here the sound present to the ears, touch hardness, softness, heat, or cold present to the touch, and so forth of others.
- An instance of this quality; hardship.
- (inorganic chemistry) The quantity of calcium carbonate dissolved in water, usually expressed in parts per million (ppm).
- The resistance to scratching, cutting, indentation or abrasion of a metal or other solid material.
- (physics) The penetrating ability of electromagnetic radiation, such as x-rays; generally, the shorter the wavelength, the harder and more penetrating the radiation.
- The measure of resistance to damage of a facility, equipment, installation, or telecommunications infrastructure when subjected to attack.
quality of being hard