ortho-
/ɔː.θə-/
"ortho" is a 5-letter English headword indexed on PlainSpell.
The verdict
“ortho-” is uncommon English (outside the top frequency list), classed as a prefix. The kind of spelling people second-guess.
- Unranked
- below top-frequency English
- 6
- letters
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Right angle, perpendicular.
Corpus desk
Index EN-ortho · ortho- · English
ortho- · unranked · 0 variants · 0 confusables
- FREQ-UNRANKED Unranked
- LEN-LONG 6 letters
- VOW-2 2 vowels
- CONFUS-0 No pairs
- VAR-0 0 variants
- BOOK-THIN "O" thin
- PHOTO-UNK Peer pending
Read with this headword: Spelling guide for this pattern
Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.
| Property | Value |
|---|---|
| Headword | ortho- |
| Language | English |
| Part of speech | Prefix |
| IPA | /ɔː.θə-/ |
| Letters | 6 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Long-tail rank of “ortho-” in English
Rare enough to double-check
ortho- is uncommon English outside the top frequency list, classed as aprefix, transcribed /ɔː.θə-/. Rarity is why readers land here mid-draft. 16 senses are on record.
The misspelling generator found no plausible variants for ortho-, since its letter sequence doesn't invite the usual edit-distance slips. No confusable counterpart is on file for this word, suggesting its spelling stands apart enough that readers rarely confuse it with something else.
Etymologically, the entry records: Learned borrowing from Ancient Greek ὀρθός (orthós). The correct English form is ortho-, spelled O-R-T-H-O--.
Definition
- 1Right angle, perpendicular.
- 2Proper, righteous, pure.
- 3To correct or fix.
- 4Same, from the same.
- 5Normal, ordinary.
- 6Straight in form.
- 7Orthorhombic crystal structure.
- 8In isomeric benzene derivatives, having the two substituents in adjacent (1,2) positions (compare meta- and para-).
- 9Having an extra proportion of water.
- 10Independent, separate.
- 11Original, primary.
- 12Parallel lines or columns.
- 13Of any molecule of the form X₂ in which the two nuclei have parallel spin.
- 14Orthopaedics.
- 15Vertical or upright in movement.
- 16Igneous.
Recorded use
Wiktionary examplesThese source excerpts show how ortho- appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
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.
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.
Etymology
Learned borrowing from Ancient Greek ὀρθός (orthós).
Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.