| heliotherapy | The treatment of disease by exposing the body to the sun's rays; the therapeutic use of sunbathing. (12 Dec 1998) |
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| heliotrope | 1. An instrument or machine for showing when the sun arrived at the tropics and equinoctial line. 2. <botany> A plant of the genus Heliotropium; called also turnsole and girasole. H. Peruvianum is the commonly cultivated species with fragrant flowers. 3. An instrument for making signals to an observer at a distance, by means of the sun's rays thrown from a mirror. 4. <chemical> See Bloodstone . Heliotrope purple, a grayish purple colour. Origin: F. Heliotrope, L. Heliotropium, Gr.; the sun + to turn, turn. See Heliacal, Trope. Source: Websters Dictionary (01 Mar 1998) |
| heliotropic | <botany> Manifesting heliotropism; turning toward the sun. Source: Websters Dictionary (01 Mar 1998) |
| heliotropism | <botany> The phenomenon of turning toward the light, seen in many leaves and flowers. Origin: Helio- + Gr. To turn. Source: Websters Dictionary (01 Mar 1998) |
| heliotypy | A method of transferring pictures from photographic negatives to hardened gelatin plates from which impressions are produced on paper as by lithography. Source: Websters Dictionary (01 Mar 1998) |
| Heliozoa | Order Heliozoida. A group of amoeboid protozoa. They are generally free floating, spherical cells with many straight, slender microtubule supported pseudopods radiating from the cell body like a sunburst. These modified pseudopods are termed axopodia. Genera include Actinophrys and Echinosphaerium. (18 Nov 1997) |
| Heliozoea | A class of protozoans (subphylum Sarcodina) distinguished by stiff radiating axopodia on all sides, usually naked, though some have a skeleton of siliceous scales and spines, but without a central capsule. They are mostly fresh water dwellers, and colonial forms are common. Origin: helio-+ G. Zoon, animal (05 Mar 2000) |
| Helisoma trivolvis | Pulmonate mollusc whose relatively simple nervous sytsem contains large identifiable cells and is consequently, like Hirudo and Aplysia a favorite preparation for studying neural mechanisms at the cellular level and in particular for studying isolated neurons in culture. (18 Nov 1997) |
| helispherical | <mathematics> Helispherical line . The rhomb line in navigation. Alternative term for spiral. Origin: Helix + spheric, spherical. Source: Websters Dictionary (01 Mar 1998) |
| helium | <element> A gas. Certain types of radiation therapy used charged, radioactive particles of helium. (16 Dec 1997) |
| helium speech | The peculiar high-pitched, often unintelligible speech sounds produced when one breathes a mixture of up to 80 per cent helium and 20 per cent oxygen. (05 Mar 2000) |
| helium-3 | The rare stable isotope of helium (1.37 parts per million of ordinary helium); produced by the beta decay of tritium. (05 Mar 2000) |
| helium-4 | The common helium isotope, making up 99.999% of natural helium; it is emitted in the form of alpha rays (which are helium nuclei), from a variety of radionuclides. (05 Mar 2000) |
| helix | <chemistry, molecular biology> A spiral structure in a macromolecule that contains a repeating pattern. (09 Oct 1997) |
| helix (snails) | A genus of chiefly eurasian and african land snails including the principal edible snails as well as several pests of cultivated plants. (12 Dec 1998) |