| porphyromonas gingivalis | A species of gram-negative, anaerobic, rod-shaped bacteria originally classified within the bacteroides genus. This bacterium produces a cell-bound, oxygen-sensitive collagenase and is isolated from the human mouth. (12 Dec 1998) |
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| porphyruria | Excretion of porphyrins and related compounds in the urine. Synonym: porphyruria, purpurinuria. (05 Mar 2000) |
| porphyry | Origin: F. Porphyre, L. Porphyrites, fr. Gr. Like purple, fr. Purple. See Purple. <geology> A term used somewhat loosely to designate a rock consisting of a fine-grained base (usually feldspathic) through which crystals, as of feldspar or quartz, are disseminated. There are red, purple, and green varieties, which are highly esteemed as marbles. <zoology> Porphyry shell, a handsome marine gastropod shell (Oliva porphyria), having a dark red or brown polished surface, marked with light spots, like porphyry. Source: Websters Dictionary (01 Mar 1998) |
| porpita | <zoology> A genus of bright-coloured Siphonophora found floating in the warmer parts of the ocean. The individuals are round and disk-shaped, with a large zooid in the center of the under side, surrounded by smaller nutritive and reproductive zooids, and by slender dactylozooids near the margin. The disk contains a central float, or pneumatocyst. Origin: NL, from Gr. Brooch. Source: Websters Dictionary (01 Mar 1998) |
| porpoise | 1. <zoology> Any small cetacean of the genus Phocaena, especially P. Communis, or P. Phocaena, of Europe, and the closely allied American species (P. Americana). The colour is dusky or blackish above, paler beneath. They are closely allied to the dolphins, but have a shorter snout. Synonym: harbor porpoise, herring hag, puffing pig, and snuffer. 2. <zoology> A true dolphin (Delphinus); often so called by sailors. <zoology> Skunk porpoise, or Bay porpoise, a North American porpoise (Lagenorhynchus acutus), larger than the common species, and with broad stripes of white and yellow on the sides. Origin: OE. Porpeys, OF. Porpeis, literally, hog fish, from L. Porcus swine + piscis fish. See Pork, and Fish. Source: Websters Dictionary (01 Mar 1998) |
| porpoises | Mammals of the family phocoenidae comprising four genera and six species found in the north pacific ocean and both sides of the north atlantic ocean and in various other seas. They differ from dolphins in that porpoises have a blunt snout and a rather stocky body while dolphins have a beaklike snout and a slender, streamlined body. They usually travel in small groups. (12 Dec 1998) |
| porporino | A composition of quicksilver, tin, and sulphur, forming a yellow powder, sometimes used by mediaeval artists, for the sake of economy, instead of gold. Origin: It. Source: Websters Dictionary (01 Mar 1998) |