| hardhead | 1. Clash or collision of heads in contest. 2. <zoology> The menhaden. See Menhaden. Block's gurnard (Trigla gurnardus) of Europe. A California salmon; the steelhead. The gray whale. See Gray whale, under Gray. A coarse American commercial sponge (Spongia dura). Source: Websters Dictionary (01 Mar 1998) |
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| hardiness | A health-enhancing behaviour trait believed to increase one's resistance to illness, characterised by a high level of personal control, commitment, and action in responding to events of daily life. Origin: M.E., fr. O.Fr. Hardi, fr. Germanic (05 Mar 2000) |
| Harding | Harold E., 20th century British pathologist. See: Harding-Passey melanoma. (05 Mar 2000) |
| Harding-Passey melanoma | <tumour> A melanin-forming tumour that arose spontaneously in a non-inbred mouse, and that is transplantable to mice of many strains but does not ordinarily metastasize. (05 Mar 2000) |
| hardness | <chemistry> Total concentration of calcium and magnesium ions, expressed as the equivalent concentration (mg/L) of calcium carbonate. Hard water is water that contains lots of calcium carbonate and other minerals. (09 Oct 1997) |
| hardness scale | A qualitative scale in which minerals are classified in order of their increasing hardness, based on the fact that the harder of two materials will scratch the softer and will not be scratched by it. The scale lists 15 substances: 1, talc; 2, gypsum; 3, calcite; 4, fluorite; 5, apatite; 6, orthoclase, periclase; 7, vitreous pure silica; 8, quartz, stellite; 9, topaz; 10, garnet; 11, tantalum carbide, fused zirconia; 12, fused alumina; 13, silicon carbide; 14, boron carbide; 15, diamond. Synonym: Mohs scale. (05 Mar 2000) |
| hardpan | <botany, ecology> A very dense soil layer caused by compaction or cementation of soil particles by organic matter, silica, sesquioxides (aluminum and iron) or calcium carbonate, for example. (09 Oct 1997) |
| hardtail | <zoology> See Jurel. Source: Websters Dictionary (01 Mar 1998) |
| hardware | The electronic component of a computer. (05 Mar 2000) |
| hardware disease | A condition of cattle, caused by the penetration of the stomach wall, usually the reticulum, by any kind of sharp object (usually metallic) which has been swallowed. Synonym: hardware disease, traumatic reticuloperitonitis. (05 Mar 2000) |
| hardwoods | Usually broad-leaved and deciduous trees. (05 Dec 1998) |
| hardy | 1. Bold; brave; stout; daring; resolu?e; intrepid. "Hap helpeth hardy man alway." (Chaucer) 2. Confident; full of assurance; in a bad sense, morally hardened; shameless. 3. Strong; firm; compact. "[A] blast may shake in pieces his hardy fabric." (South) 4. Inured to fatigue or hardships; strong; capable of endurance; as, a hardy veteran; a hardy mariner. 5. Able to withstand the cold of winter. Plants which are hardy in Virginia may perish in new England. Half-hardy plants are those which are able to withstand mild winters or moderate frosts. Origin: F.hardi, p. P. Fr. OF. Hardir to make bold; of German origin, cf. OHG. Hertan to harden, G. Harten. See Hard. Source: Websters Dictionary (01 Mar 1998) |
| Hardy, George | <person> English mathematician, 1877-1947. See: Hardy-Weinberg equilibrium, Hardy-Weinberg law. (05 Mar 2000) |
| Hardy, LeGrand | <person> U.S. Ophthalmologist, 1895-1954. See: Hardy-Rand-Ritter test. (05 Mar 2000) |
| Hardy-Rand-Ritter test | A test for colour vision deficiency using pseudoisochromatic cards. These excellent cards have not been reprinted by the American Optical Co. Since the plates were accidentally destroyed in 1965. (05 Mar 2000) |