| OCTOTHORPES | • octothorpes n. Plural of octothorpe. |
| ORTHOEPISTS | • orthoepists n. Plural of orthoepist. • orthoëpists n. Plural of orthoëpist. • ORTHOEPIST n. one who is skilled in orthoepy. |
| ORTHOPEDIST | • orthopedist n. (Medicine) A surgeon who specializes in orthopedics. • ORTHOPEDIST n. a specialist in orthopedics, also ORTHOPAEDIST. |
| ORTHOPTISTS | • orthoptists n. Plural of orthoptist. • ORTHOPTIST n. one who practises orthoptics, the science of correct vision. |
| PHOTOMETERS | • photometers n. Plural of photometer. • PHOTOMETER n. an instrument for measuring light intensity. |
| PHOTORESIST | • photoresist n. A light-sensitive film used in photolithography and photoengraving. • PHOTORESIST n. an organic material that polymerizes on exposure to ultraviolet light and in that form resists attack by acids and solvents. |
| PHOTOSETTER | • photosetter n. A photocomposer; a machine for photosetting. • PHOTOSETTER n. an apparatus for photosetting. |
| PHOTOTROPES | • PHOTOTROPE n. a substance exhibiting phototropism, movement directed by light. |
| PHOTOTROPHS | • phototrophs n. Plural of phototroph. • PHOTOTROPH n. a plant which uses light to generate energy needed to absorb nutrients. |
| PHYTOSTEROL | • phytosterol n. (Biochemistry, botany) Any of a group of steroid alcohols, phytochemicals naturally occurring in plants… • PHYTOSTEROL n. any of various sterols derived from plants. |
| PROTOPHYTES | • protophytes n. Plural of protophyte. • PROTOPHYTE n. any unicellular plant, or plant forming only a plasmodium, having reproduction only by fission, gemmation, or cell division. |
| PROTOTROPHS | • prototrophs n. Plural of prototroph. • PROTOTROPH n. a bacterium feeding only on inorganic matter. |
| THIXOTROPES | • THIXOTROPE n. a thixotropic substance. |
| TOPNOTCHERS | • topnotchers n. Plural of topnotcher. • top-notchers n. Plural of top-notcher. • TOPNOTCHER n. crude oil after some of its lighter constituents have been removed by distillation. |
| TRAPSHOOTER | • trapshooter n. A participant in the sport of trapshooting. • TRAPSHOOTER n. a person who engages in trapshooting. |
| TROPHOBLAST | • trophoblast n. (Cytology) The membrane of cells that forms the wall of a blastocyst during early pregnancy, providing… • TROPHOBLAST n. the outermost layer of cells in the morula that attaches the fertilized ovum to the uterine wall and acts as a nutritive pathway. |
| TROPHOTAXES | • TROPHOTAXIS n. chemotaxis and chemotropism where the stimulating substance is food. |
| TROPHOTAXIS | • TROPHOTAXIS n. chemotaxis and chemotropism where the stimulating substance is food. |
| TROPOPHYTES | • tropophytes n. Plural of tropophyte. • TROPOPHYTE n. a plant adapted to alterations of moisture and drought. |