| ERIOPHORUM | • Eriophorum prop.n. A taxonomic genus within the family Cyperaceae – cottongrass, found in acidic bogs, especially in the Arctic. • ERIOPHORUM n. a plant of the cotton-grass genus. |
| ODORIPHORE | • ODORIPHORE n. the group of atoms in an odorous molecule responsible for its odour. |
| OROGRAPHIC | • orographic adj. Of or pertaining to the physical features of mountains, or to orography. • orographic adj. (Meteorology) Of or pertaining to the effects of mountains on weather. • OROGRAPHIC adj. relating to orography, the description of mountains, also OROGRAPHICAL. |
| ORPHARIONS | • orpharions n. Plural of orpharion. • ORPHARION n. a large lute-like stringed instrument with six to nine metal strings, also ORPHEOREON. |
| ORTHOPRISM | • ORTHOPRISM n. in monoclinic crystals, a form consisting of two faces parallel to the orthodiagonal. |
| PORPHYRIOS | • porphyrios n. Plural of porphyrio. • PORPHYRIO n. any bird of the purple-coot genus Porphyrio. |
| PORPHYROID | • porphyroid n. (Mineralogy) A crystalline and schistose rock containing porphyritic crystals of feldspar. • PORPHYROID n. a metamorphic rock having a texture characterized by large crystals set in a finer groundmass. |
| PROHIBITOR | • prohibitor n. One who prohibits. • PROHIBITOR n. one who prohibits, also PROHIBITER. |
| PRONEPHROI | • pronephroi n. Plural of pronephros. • PRONEPHROS n. a primitive kidney that disappears early in embryonic development. |
| PYORRHOEIC | • pyorrhoeic adj. Alternative form of pyorrheic. • pyorrhœic adj. Obsolete form of pyorrheic. • PYORRHOEIC adj. relating to pyorrhoea, suppuration in the sockets of the teeth, also PYORRHEAL, PYORRHEIC, PYORRHOEAL. |
| PYROPHORIC | • pyrophoric adj. Spontaneously igniting in air, especially when in a finely divided state. • pyrophoric adj. Producing sparks, especially by friction. • pyrophoric adj. (Fire investigation) Able to oxidize with exposure to atmospheric oxygen at normal temperatures. |
| RHEOTROPIC | • rheotropic adj. Pertaining to or exhibiting rheotropism. • RHEOTROPIC adj. relating to a rheotrope, an instrument for reversing the direction of an electric current. |
| RHIZOMORPH | • rhizomorph n. A rootlike structure, consisting of a dense mass of hyphae, in many fungi. • RHIZOMORPH n. a rootlike mass of fungal hyphae. |
| RHIZOPHORE | • rhizophore n. (Botany) The structure bearing the true roots in certain species of Selaginella. • RHIZOPHORE n. a specialised leafless stem which bears roots, as in Selaginella. |
| SPIROPHORE | • spirophore n. (Historical) A device for inducing artificial respiration by means of an airtight case for the body and an air pump. • SPIROPHORE n. an apparatus for inducing artificial respiration by means of an airtight case for the body and an air pump. |