or·tho·cen·ter 
(ôrthō-sĕn′tər)
(ôrthō-sĕn′tər)n.
The point of intersection of the three altitudes of a triangle.
- radiolysis
- radiolytic
- radioman
- radiometer
- radiometric
- radiometric dating
- radiometry
- radiomimetic
- radionuclide
- radiopacity
- radiopaque
- radiopharmaceutical
- radiophone
- radiophonic
- radiophoto
- radiophotograph
- radiophotography
- radioscopic
- radioscopical
- radioscopy
- radiosensitive
- radiosensitivity
- radiosonde
- radio spectrum
- radiosurgery