ortho-

Prefix

ortho-

1. Right angle, perpendicular.
   • In this sense, it is the angle that is "right" or straight rather than the line; orthogon is a right-angle triangle, orthocentric is a tetrahedron where all three pairs of opposite edges are perpendicular, orthoclastic is a crystal whose cleavage planes are at right angles.

   Synonyms:

   cross-

2. Proper, righteous, pure.
   • E.g., orthorexia is an unhealthy fixation with healthy or righteous eating, an orthotaxon is a true taxon based biological relationships rather than form, orthology is speech which is proper, orthoquartzite is very pure quartz sandstone.

   Synonyms:

   eu-

3. To correct or fix.
   • E.g., orthophotography is the geometrical correction of aerial photographs, orthoptics is the treatment of muscular irregularities of the eye, orthodontics is the correcting of misaligned teeth.

   Synonyms:

   fix-

4. Same, from the same.
   • E.g., An orthocousin, unlike a cross-cousin, is on the same side of the family; orthogamy is when a plant's ovules are fertilized by pollen from the same plant; orthochronous is a transformation which preserves the direction of time.

   Synonyms:

   ipsi-

5. Normal, ordinary.
   • E.g., orthocclusion is normal occlusion, orthodromic is when neurological impulses are passed in the normal direction, orthogravitropism is the ordinary effect of gravity on plants

   Synonyms:

   normo-

6. Straight in form.
   • E.g., orthoconic is a mollusc shell that is straight rather than spiraled, orthodentin is dentin composed of straight tubes, orthognathous is straight-jawed. .

   Synonyms:

   recti-

7. Orthorhombic crystal structure.
   • E.g., orthochrysotile is an orthorhombic chrysotile, orthopyroxene is a pyroxene that forms orthorhombic crystals, orthohexagonal is having orthorhombic hexagonal symmetry.
8. In isomeric benzene derivatives, having the two substituents in adjacent (1,2) positions (compare meta- and para-).
   • E.g., orthophenylene, orthosubstitution, orthocleavage.
9. Having an extra proportion of water.
   • E.g., orthophosphate, orthosilicate, orthoferrite.
10. Independent, separate.
    • E.g., orthogonal as in statistically independent, orthopair is a pair of disjoint subsets, orthogonal in the sense of two aspects of a software problem are able to be treated separately.
11. Original, primary.
    • E.g., orthonasal is the first direction from which olfaction happens; orthosteric is the original and unmodulated binding site; orthotone is when a speaker retains the accent.

    Synonyms:

    proto-

12. Parallel lines or columns.
    • E.g., orthostyle is a series of columns in architecture, an ortholinear keyboard has the keys aligned in straight columns, an orthographic projection has its rays parallel.

    Synonyms:

    para-