Ortho- is a Greek prefix meaning “straight”, “upright”, “right” or “correct”. Ortho may refer to: Ortho, Belgium, a village in the Belgian province of Luxembourg In science arene substitution patterns, two substituents that occupy adjacent positions on an aromatic ring Chlordane, an organochlorine compound that was used as a pesticide In mathematics: Orthogonal, a synonym for perpendicular Orthonormal, the property that a collection of vectors are mutually perpendicular and each of unit magnitude Orthodrome, a synonym for great circle, a geodesic on the sphere Orthographic projection, a parallel projection onto a perpendicular plane In medicine: Orthomyxovirus, a family of viruses to which influenza belongs Orthodontics, a specialty of dentistry concerned with the study and treatment of malocclusions Orthopedic, the study of the musculoskeletal system Ortho-DOT, a psychedelic drug Ortho-cept and Ortho Tri-cyclen, kinds of oral contraceptive drug In theology: Orthodoxy, right (correct) belief Orthopraxy, right (correct) action In business: Ortho Pharmaceutical, which merged into Ortho-McNeil Pharmaceutical before being bought by Johnson & Johnson Ortho-Clinical Diagnostics, another subsidiary of Johnson & Johnson Ortho, a lawn care and pesticide company owned by the Scotts Miracle-Gro Company See also Orthos (disambiguation) Ortho Mode Transducer Orthochromatic Orthophotography Orthoptera