| ortho- | 1. <prefix> A combining form signifying straight, right, upright, correct, regular; as, orthodromy, orthodiagonal, orthodox, orthographic. 2. <chemistry> Connection with, or affinity to, one variety of isomerism, characteristic of the benzene compounds; contrasted with meta- or para-; as, the ortho position; hence, designating any substance showing such isomerism; as, an ortho compound. In the graphic representation of the benzene nucleus (see Benzene nucleus, under Benzene), provisionally adopted, any substance exhibiting double substitution in adjacent and contiguous carbon atoms, as 1 & 2, 3 & 4, 4 & 5, etc, is designated by ortho-; as, orthoxylene; any substance exhibiting substitution of two carbon atoms with one intervening, as 1 & 3, 2 & 4, 3 & 5, 4 & 6, etc, by meta-; as, resorcin or metaxylene; any substance exhibiting substitution in opposite parts, as 1 & 4, 2 & 5, 3 & 6, by para-; as, hydroquinone or paraxylene. Origin: Gr. Straight; akin to Skr. Rdhva upright, vrdh to grow, to cause to grow. (29 Oct 1998) |
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| ortho-halobenzoate 1,2-dioxygenase | <enzyme> A three-component broad substrate-specific enzyme that requires oxygen, NADH, fe(ii) and flavin adenine dinucleotide; degrades 2,4-, 2,5-dichloro-, 2-chloro (& a variety of other substituted halobenzoates) to 4-chlorocatechol and catechol Registry number: EC 1.14.12.- (26 Jun 1999) |
| orthoacid | An acid in which the number of hydroxyl groups equals the valence of the acid-forming element; e.g., C(OH)4, orthocarbonic acid. When there is no such acid, the one that most nearly approaches this condition is sometimes called an orthoacid; e.g., OP(OH)3, orthophosphoric acid. (05 Mar 2000) |
| orthoarteriotony | Normal blood pressure. Origin: ortho-+ G. Arteria, artery, + tonos, tension (05 Mar 2000) |
| orthobiosis | Rarely used term for correct living, both hygienically and morally. Origin: ortho-+ G. Biosis, life (05 Mar 2000) |
| orthocaine | The methyl ester of 3-amino-4-hydroxybenzoic acid; a surface anaesthetic agent usually used in dusting powder form. (05 Mar 2000) |
| orthocarbonic | <chemistry> Designating a complex ether, C.(OC2H5)4, which is obtained as a liquid of a pleasant ethereal odour by means of chlorpicrin, and is believed to be a derivative of the hypothetical normal carbonic acid, C.(OH)4. Origin: Ortho- + carbonic. Source: Websters Dictionary (01 Mar 1998) |
| orthocenter | <geometry> That point in which the three perpendiculars let fall from the angles of a triangle upon the opposite sides, or the sides produced, mutually intersect. Origin: Ortho- + center. Source: Websters Dictionary (01 Mar 1998) |
| orthocephalic | Having a head well proportioned to height; denoting a skull with a vertical index between 70 and 75. See: metriocephalic. Synonym: orthocephalous. Origin: ortho-+ G. Kephale, head (05 Mar 2000) |
| orthocephalous | Having a head well proportioned to height; denoting a skull with a vertical index between 70 and 75. See: metriocephalic. Synonym: orthocephalous. Origin: ortho-+ G. Kephale, head (05 Mar 2000) |
| orthoceras | <paleontology> An extinct genus of Paleozoic Cephalopoda, having a long, straight, conical shell. The interior is divided into numerous chambers by transverse septa. Origin: NL, fr. Gr. Straight + a horn. Source: Websters Dictionary (01 Mar 1998) |
| orthoceratite | <zoology> An orthoceras; also, any fossil shell allied to Orthoceras. Origin: Ortho- + Gr, a horn. Source: Websters Dictionary (01 Mar 1998) |
| orthochorea | A form of chorea in which the spasms occur only or chiefly when the patient is in the erect posture. (05 Mar 2000) |
| orthochromatic | Denoting any tissue or cell that stains the colour of the dye used, i.e., the same colour as the dye solution with which it is stained. Synonym: euchromatic, orthochromophil, orthochromophile. Origin: ortho-+ G. Chroma, colour (05 Mar 2000) |
| orthochromophil | Orthochromophile Synonym: orthochromatic. Origin: ortho-+ G. Chroma, colour, + philos, fond (05 Mar 2000) |
| toluene ortho-monooxygenase | <enzyme> Enzyme from pseudomonas sp. Strain js150 acts on both toluene and benzene; amino acid sequence has been determined; also hydroxylates cresol to 3-methylcatechol Registry number: EC 1.13.12.- Synonym: toluene 2-monooxygenase, toluene-benzene-2-monooxygenase (26 Jun 1999) |
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