induration

Etymology

From Middle English induracioun, from Old French induracion (“hardness, obstinacy”) or directly from Medieval Latin induratiō.

noun

1. Hardness.
   The voice was harder than I had known, and not only in stony reaction to long floods of wholly just selfpity, also roughened with gin and smoke, perhaps also assimilated to New York induration, the hardness of culture as well as of pain. 1980. Anthony Burgess, Earthly Powers
2. Process of becoming hard.
3. (medicine) Hardening of an area of the body as a reaction to inflammation, hyperemia, or neoplastic infiltration.
4. (medicine) An area or part of the body that has undergone such a reaction. Most often this term is used to describe dermatologic findings.
   Both erythema and induration appear to be adequate indices of tuberculin sensitivity. 2005. Kimura, et al. "Comparison of erythema and induration as results of tuberculin tests." Int J Tuberc Lung Dis. 2005;9(8):853-7. PMID 16104630
   The erythema had spread to 20 cm, and the central induration had spread to 9 cm. 2005. Race, et al. "Painful nodule with induration and spreading erythema." Baylor University Medical Center Proceedings. 2005;18(4):401–404
5. (geology) The quality of non-friability; the extent to which a rock does not crumble; rock strength.
   "Induration is a measure of rock "strength" and is defined as the ratio of the measured frame modulus to the maximum frame modulus allowed by the Gassmann-Biot model." Spratt, R. S.; Goins, N. R. and Fitch, T. J. (1993) "Pseudo-shear — The analysis of AVO." Castagna, John P. and Backus, Milo M. (eds.) Offset-Dependent Reflectivity — Theory and Practice of AVO Analysis. Series: Investigation in Geophysics volume 8. Tulsa : Society of Exploration Geophysicistspp. 37-56, page 37, isbn 978-1-56080-059-0.
6. (geology) The process of the strengthening of rocks by heating, compaction or cementation, or a combination thereof.
   "Induration of carbonate rocks proceeds predominately in the early stages (prior to diagenesis) by compaction and expulsion of fluids." Whittaker, Alun (1985) Formation Evaluation: Geological Procedures Dordrecht : Springer Verlag page 104, isbn 978-94-010-8861-9.
   "At a given degree of induration, massive rocks of sandstone, siltstone, and limestone are the strongest, while shaly rocks with more or less parallel, closely spaced separation surfaces created during sedimentation in thin layers are the weakest." Committee on Underground Coal Mine Safety (1982) Toward Safer Underground Coal Mines Washington, D.C. : National Academy Press, page 32, isbn 978-0-309-03298-8.