ortho

/AO1 R TH OW0/
noun
  1. 1

    An isomer of a benzene derivative having two substituents adjacent on the ring.

  2. 2

    A certain type of flat eyepiece.

  3. 3

    An orthochromatic plate.

  4. 4

    (imaging) An orthophoto.

  5. 5

    Orthopedics.

Source: https://en.wiktionary.org/wiki/ortho