n.; pl. Anthelia [ Pref. anti + Gr. &unr_; sun. ] (Meteor.) A halo opposite the sun, consisting of a colored ring or rings around the shadow of the spectator's own head, as projected on a cloud or on an opposite fog bank. [ 1913 Webster ]

n.; pl. Aphelia [ Gr. &unr_; + &unr_; sun. ] (Astron.) That point of a planet's or comet's orbit which is most distant from the sun, the opposite point being the perihelion. [ 1913 Webster ]

a. [ Gr. &unr_; + &unr_; sun + &unr_; belonging to a turning. ] Turning away from the sun; -- said of leaves, etc. Darwin. [ 1913 Webster ]

n. The habit of bending from the sunlight; -- said of certain plants. [ 1913 Webster ]

a. [ Gr. &unr_; through, at variance + &unr_; sun + &unr_; turning. ] (Bot.) Relating or, or manifesting, diaheliotropism. [ 1913 Webster ]

n. (Bot.) A tendency of leaves or other organs of plants to have their dorsal surface faced towards the rays of light. [ 1913 Webster ]

a. [ Epithelium + -oid. ] (Anat.) Like epithelium; as, epithelioid cells. [ 1913 Webster ]

‖n. [ NL. See Epithelium, and -oma. ] (Med.) A malignant growth containing epithelial cells; -- called also epithelial cancer. [ 1913 Webster ]

A combining form from Gr. "h`lios the sun.

{ } a. [ Helio- + centric, centrical: cf. F. héliocentrique. ] (Astron.) pertaining to the sun's center, or appearing to be seen from it; having, or relating to, the sun as a center; -- opposed to geocentrical. [ 1913 Webster ]

Heliocentric parallax. See under Parallax. --
Heliocentric place,
latitude,
longitude, etc. (of a heavenly body), the direction, latitude, longitude, etc., of the body as viewed from the sun. [ 1913 Webster ]

n. [ Helio- + Gr. chrw^ma color. ] A photograph in colors. R. Hunt. [ 1913 Webster ]

a. Pertaining to, or produced by, heliochromy. [ 1913 Webster ]

n. The art of producing photographs in color. [ 1913 Webster ]

n. [ Helio- + -gram. ] A message transmitted by a heliograph. [ Webster 1913 Suppl. ]

n. [ Helio- + -graph. ] [ 1913 Webster ]

1. A picture taken by heliography; a photograph. [ 1913 Webster ]

2. An instrument for taking photographs of the sun. [ 1913 Webster ]

3. An apparatus for telegraphing by means of the sun's rays. See Heliotrope, 3. [ 1913 Webster ]

v. t. 1. To telegraph, or signal, with a heliograph. [ Webster 1913 Suppl. ]

2. To photograph by sunlight. [ Webster 1913 Suppl. ]

a. (Astron.) 1. Of or pertaining to a description of the sun. [ Webster 1913 Suppl. ]

☞ Heliographic longitudes and latitudes of spots on the sun's surface are analogous to geographic longitudes and latitudes of places on the earth. [ Webster 1913 Suppl. ]

2. Of or pertaining to heliography or a heliograph; made by heliography. [ 1913 Webster ]

Heliographic chart. See under Chart. [ 1913 Webster ]

n. 1. [ Helio- + -graphy. ] The description of the sun. [ Webster 1913 Suppl. ]

2. The system, art, or practice of telegraphing, or signaling, with the heliograph. [ Webster 1913 Suppl. ]

3. An early photographic process invented by Nicéphore Niepce, and still used in photo-engraving. It consists essentially in exposing under a design or in a camera a polished metal plate coated with a preparation of asphalt, and subsequently treating the plate with a suitable solvent. The light renders insoluble those parts of the film which is strikes, and so a permanent image is formed, which can be etched upon the plate by the use of acid. [ Webster 1913 Suppl. ]

4. Photography. [ Archaic. ] R. Hunt. [ 1913 Webster ]

n. [ F. héliogravure. ] 1. The process of photographic engraving. [ 1913 Webster ]

2. A plate or picture made by the process of heliogravure. [ Webster 1913 Suppl. ]

n. [ Helio- + Gr. &unr_; servant, worshiper. ] A worshiper of the sun. [ 1913 Webster ]

n. [ Helio- + Gr. &unr_; service, worship. ] Sun worship. See Sabianism. [ 1913 Webster ]

n. [ Helio- + -lite. ] (Paleon.) A fossil coral of the genus Heliolites, having twelve-rayed cells. It is found in the Silurian rocks. [ 1913 Webster ]

n. [ Helio- + -meter: cf. F. héliomètre. ] (Astron.) An instrument devised originally for measuring the diameter of the sun; now employed for delicate measurements of the distance and relative direction of two stars too far apart to be easily measured in the field of view of an ordinary telescope.

{ } a. Of or pertaining to the heliometer, or to heliometry. [ 1913 Webster ]

n. The apart or practice of measuring the diameters of heavenly bodies, their relative distances, etc. See Heliometer. [ 1913 Webster ]

‖n. [ NL., fr. Gr. &unr_; the sun + &unr_; a passage, pore. ] (Zool.) An East Indian stony coral now known to belong to the Alcyonaria; -- called also blue coral. [ 1913 Webster ]

n. [ Helio- + -scope: cf. F. hélioscope. ] (Astron.) A telescope or instrument for viewing the sun without injury to the eyes, as through colored glasses, or with mirrors which reflect but a small portion of light. -- He`li*o*scop`ic a. [ 1913 Webster ]

n. [ Helio- + Gr. &unr_; placed, standing, fr. &unr_; to place, stand: cf. F. héliostate. ] An instrument consisting of a mirror moved by clockwork, by which a sunbeam is made apparently stationary, by being steadily directed to one spot during the whole of its diurnal period; also, a geodetic heliotrope. [ 1913 Webster ]

n. [ F. héliotrope, L. heliotropium, Gr. &unr_;; &unr_; the sun + &unr_; to turn, &unr_; turn. See Heliacal, Trope. ] 1. (Anc. Astron.) An instrument or machine for showing when the sun arrived at the tropics and equinoctial line. [ 1913 Webster ]

2. (Bot.) A plant of the genus Heliotropium; -- called also turnsole and girasole. Heliotropium Peruvianum is the commonly cultivated species with fragrant flowers. [ 1913 Webster ]

3. (Geodesy & Signal Service) An instrument for making signals to an observer at a distance, by means of the sun's rays thrown from a mirror. [ 1913 Webster ]

4. (Min.) See Bloodstone (a). [ 1913 Webster ]

Heliotrope purple, a grayish purple color. [ 1913 Webster ]

n. The person at a geodetic station who has charge of the heliotrope. [ 1913 Webster ]

a. (Bot.) Manifesting heliotropism; turning toward the sun. [ 1913 Webster ]

n. [ Helio- + Gr. &unr_; to turn. ] (Bot.) The phenomenon of turning toward the light, seen in many leaves and flowers. [ 1913 Webster ]

n. [ Helio- + -type. ] A picture obtained by the process of heliotypy. [ 1913 Webster ]

a. Relating to, or obtained by, heliotypy. [ 1913 Webster ]

n. A method of transferring pictures from photographic negatives to hardened gelatin plates from which impressions are produced on paper as by lithography. [ 1913 Webster ]

‖n. pl. [ NL., fr. Gr. &unr_; the sun + zw^, on an animal. ] (Zool.) An order of fresh-water rhizopods having a more or less globular form, with slender radiating pseudopodia; the sun animalcule.

n. [ Gr. 'o`ros mountain + helio- + -graph. ] (Photog.) A camera for obtaining a circular panoramic view of the horizon. The photographic plate is placed horizontally with a vertical lens above. A mirror of peculiar shape reflects light from the entire horizon to the lens, by means of which it is focused upon the plate. [ Webster 1913 Suppl. ]

n.; pl. Parhelia [ L. parelion, Gr. &unr_;, &unr_;; para` beside + &unr_; the sun. ] A mock sun appearing in the form of a bright light, sometimes near the sun, and tinged with colors like the rainbow, and sometimes opposite to the sun. The latter is usually called an anthelion. Often several mock suns appear at the same time. Cf. Paraselene. [ 1913 Webster ]

{ } n.; pl. Perihelia [ NL., fr. Gr. peri` about, near + "h`lios the sun.] (Astron.) That point of the orbit of a planet or comet which is nearest to the sun; -- opposed to aphelion. [1913 Webster]

n. [ Photo- + heliograph. ] (Physics) A modified kind of telescope adapted to taking photographs of the sun. [ 1913 Webster ]

n. [ Photo- + heliometer. ] (Astron.) A double-lens instrument for measuring slight variations of the sun's diameter by photography, utilizing the common chord of two overlapping images. [ Webster 1913 Suppl. ]

n. [ Gr. &unr_; fire + &unr_; sun + -meter. ] (Physics) An instrument for measuring the direct heating effect of the sun's rays. [ 1913 Webster ]

n. [ Spectrum + heloi- + -gram. ] (Astrophysics) A photograph of the sun made by monochromatic light, usually of the calcium line (k), and showing the sun's faculae and prominences. [ Webster 1913 Suppl. ]

n. (Astrophysics) An apparatus for making spectroheliograms, consisting of a spectroscopic camera used in combination with a telescope, and provided with clockwork for moving the sun's image across the slit. -- Spec`tro*he`li*o*graph"ic a. [Webster 1913 Suppl.]