| MOTORBOATER | • motorboater n. Someone who pilots a motorboat. • MOTORBOATER n. one who drives a motorboat. |
| MOTORSPORTS | • motorsports n. Plural of motorsport. |
| ORTHOBORATE | • orthoborate n. (Inorganic chemistry) Any anion derived from orthoboric acid; any salt containing this anion. • ORTHOBORATE n. a salt of orthoboric acid. |
| ORTHOPTERON | • orthopteron n. Alternative form of orthopteran. • ORTHOPTERON n. any member of the Orthoptera, an order of mandibulate insects, also ORTHOPTERAN. |
| ORTHOTROPIC | • orthotropic adj. (Botany) Growing vertically, either upwards or downwards. • orthotropic adj. (Engineering) Having material properties that differ along three mutually orthogonal twofold axes of… • ORTHOTROPIC adj. growing along a vertical axis. |
| PROTONOTARY | • protonotary n. Alternative spelling of prothonotary. • PROTONOTARY n. a court clerk; a chief clerk of any of various courts of law, also PROTHONOTARY. |
| PROTOTROPHS | • prototrophs n. Plural of prototroph. • PROTOTROPH n. a bacterium feeding only on inorganic matter. |
| PROTOTROPHY | • prototrophy n. The condition of being a prototroph. • PROTOTROPHY n. the state of being prototrophic. |
| STROBOTRONS | • strobotrons n. Plural of strobotron. • STROBOTRON n. a gas-filled electron tube used esp. as a source of bright flashes of light for a stroboscope. |
| THERMOMOTOR | • THERMOMOTOR n. an engine that produces force from the expansion of a heated fluid. |
| TRAITORHOOD | • traitorhood n. The quality of being a traitor. • TRAITORHOOD n. the state of being a traitor. |
| TROCHOTRONS | • TROCHOTRON n. a trochoidal magnetron, high-frequency counting tube which deflects a beam on to radially disposed electrodes. |