English Reference
adjective · noun

orthogonal

adj. · n.
US /ɔɹˈθɔɡənəɫ/ or·thog·o·nal

  1. 01 C1 Advanced Technical Math

    adj.meeting or crossing at a 90-degree angle.

    adj.relating to or composed of right angles; perpendicular. Non-gradable in its geometric sense.

    Simple

    The two walls are orthogonal to each other, forming a perfect corner.

    In context

    The architect designed the floor plan using an orthogonal grid to ensure all structural supports met at precise right angles.

    Usage

    Usually followed by the preposition 'to'.

    perpendicularright angled
  2. 02 C1 Advanced AcademicFormal

    adj.describing two things that are separate and do not affect each other.

    adj.statistically independent or conceptually irrelevant to one another; able to be treated separately without interference.

    Simple

    The cost of the project is orthogonal to the quality of the final product.

    In context

    In software design, the user interface should be orthogonal to the underlying data logic so that changes in one do not break the other.

    Teacher's tip

    This sense is common in computer science and high-level business strategy to describe 'uncoupled' ideas.

  3. 03 C2 Proficiency Technical Math

    adj.describing vectors that have a zero result when multiplied in a specific way.

    adj.of a pair of vectors: having an inner product of zero. Also applied to square matrices where the transpose equals the inverse.

    Simple

    The professor proved that the two vectors were orthogonal.

    In context

    The transformation is represented by an orthogonal matrix, which ensures that the lengths of the vectors and the angles between them are preserved.

  4. 04 C2 Proficiency Technical Math

    n.a line that is at a right angle to another line.

    n.a line or vector that is perpendicular to another given line or plane.

    Simple

    Draw an orthogonal from the center point to the edge of the circle.

    In context

    The calculation requires you to determine the length of the orthogonal dropped from the vertex to the opposite side of the triangle.

A further condition they set was that the two Latin squares should be orthogonal, meaning that superimposing them would produce every possible ordered pair of symbols exactly once.

Phys.org· 14 Aug 2026

From Middle French orthogonal, in turn from Medieval Latin orthogōnālis and Latin orthogōnius (“right-angled”), ultimately from Ancient Greek ὀρθογώνιος (orthogṓnios, “rectangular”). By surface analysis, ortho- + -gon + -al.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Ancient Greek ὀρθογώνιος
Level C1 · Advanced
Frequency Occasional
Updated