Here are some examples of words using the prefix "ortho-":
* Orthogonal: Perpendicular or at right angles.
* Orthodontics: The branch of dentistry dealing with the correction of irregularities of the teeth.
* Orthopedics: The branch of medicine dealing with the correction of deformities and injuries of the musculoskeletal system.
* Orthography: The study of the correct spelling and pronunciation of words.