A combining form signifying straight, right, upright, correct, regular; as, orthodromy, orthodiagonal, orthodox, orthographic
A combining form (also used adjectively) The one of several acids of the same element (as the phosphoric acids), which actually occurs with the greatest number of hydroxyl groups; as, orthophosphoric acid
Short for Orthochromatic – a high contrast film that's sensitive to all colour other than red and deep orange As a result these can be handled under red safelight conditions and are designed primarily for reproducing halftone images or artistic black and white shots that have few mid tones
Connection with, or affinity to, one variety of isomerism, characteristic of the benzene compounds; contrasted with meta- or para-; as, the ortho position; hence, designating any substance showing such isomerism; as, an ortho compound