Oku-iwa Rock ({{coord|68|42|S|40|50|E|display=inline,title}}) is a substantial rock exposure just east of Oku-iwa Glacier on the coast of Queen Maud Land. Mapped from surveys and air photos by Japanese Antarctic Research Expedition (JARE), 1957–62, and named Oku-iwa (interior rock). The name presumably suggests the interior position of the rock with respect to the minor recession of the coast along which the rock is located.

• Orthogonal ligand-protein pair
• Orthogonal (novel)
• Orthogonal projections
• Orthogonal range searching
• Orthogonal (spacetime)
• Orthogonikleithrus
• Orthogonioptelum
• Orthogonis
• Orthogonis stygia
• Orthogonium
• Orthogonoceros
• Orthographically
• Orthographics
• Ortho Gynest
• Ortho-Gynest
• Orthoidea
• Ortho-iodohippurate
• Ortho-Iodohippuric acid
• Orthokaryotes
• Orthokine
• Ortholasma
• Ortholasma colossus
• Ortholasma coronadense
• Ortholasma pictipes
• Ortholasma rugosum