ortho-, orth-

(Greek: right, straight, correct, true; designed to correct)

The art of sailing in a direct course, or on the arc of a great circle, which is the shortest distance between any two points on the surface of the globe; great-circle sailing.
An authority on pronunciation.
1. The art of correct pronunciation.
2. Generally acceptable pronunciations.
1. In botany, immediate or direct self-fertilization of the ovary; as, by the stamens of the same flower.
2. Direct fertilization in plants, as when the pollen fertilizing the ovules comes from the stamens of the same blossom; opposed to heterogamy.
1. a biological principle that the evolution of an animal species is in a given direction, governed by intrinsic factors, and independent of external factors.
2. The doctrine that the phylogenetic evolution of organisms takes place systematically in a definite direction and not accidentally in many directions; variation is predetermined by the germ plasm.
Eugenics or improvements in the genetic constitution of the human species by selective breeding.

Orthogenics refers to scientific endeavors to increase the proportion of people with better than average genetic endowment through selective mating of marriage partners.

A reference to normal blood sugar concentration.
A specialty dealing with the etiology (the causes or origins) and treatment of abnormal relationships between the bones of the jaws.
1. Relating to orthognathia.
2. Having a face without a projecting jaw.
orthognathic surgery
The surgical correction of deformities or malpositions of the jaw.
The characteristic of having non-projecting jaws.
1. Having the lower jaw correctly in line with the upper jaw.
2. Straight jaws which have the front of the head, or the skull, nearly perpendicular, not retreating backwards above the jaws.
The quality or state of not having the lower parts of the face projecting.
A rectangular figure.
1. Having or determined by right angles; perpendicular.
2. An area of a computer display in which units of distance are the same horizontally and vertically so that there is no distortion.