| pyrena | Origin: NL, fr. Gr, the stone of fruit. <botany> A nutlet resembling a seed, or the kernel of a drupe. Source: Websters Dictionary (01 Mar 1998) |
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| pyrenaemia | A condition characterised by the presence of nucleated red blood cells. Origin: G. Pyren, the pit of a fruit, + haima, blood (05 Mar 2000) |
| pyrene | <botany> The 'stone' (endocarp plus seed) of a succulent fruit. Compare: berry, drupe. (09 Oct 1997) |
| pyrenes | <chemical> A group of condensed ring hydrocarbons. Pharmacological action: carcinogens. (12 Dec 1998) |
| Pyrenochaeta romeroi | One of the numerous species of true fungi capable of causing mycetoma in humans. (05 Mar 2000) |
| pyrenoid | <plant biology> Small body found within some chloroplasts, that may contain protein. In green algae may be involved in starch synthesis. (18 Nov 1997) |
| pyrethrin | <chemistry> A substance resembling, and isomeric with, ordinary camphor, and extracted from the essential oil of feverfew. Synonym: Pyrethrum camphor. Origin: NL. Pyrethrum, generic name of feverfew, Gr. Feverfew. Source: Websters Dictionary (01 Mar 1998) |
| pyrethrine | <chemistry> An alkaloid extracted from the root of the pellitory of Spain (Anacyclus pyrethrum). Source: Websters Dictionary (01 Mar 1998) |
| pyrethrins | <chemical> The active insecticidal constituent of pyrethrum flowers. Pyrethrin I is the pyretholone ester of chrysanthemummonocarboxylic acid and pyrethrin II is the pyretholone ester of chrysanthemumdicarboxylic acid monomethyl ester. Pharmacological action: insecticide, botanical. (12 Dec 1998) |
| pyrethroids | Synthetic pyrethrin derivatives that are used as insecticides; as a class these agents are less toxic to mammals than are other effective insecticides. (05 Mar 2000) |
| pyrethrolone | 2-Methyl-4-oxo-3-(2,4-pentanedienyl)-2-cyclopentenol, a constituent of the pyrethrins. (05 Mar 2000) |
| pyrethrum | <plant biology> A natural insecticide that is extracted from chrysanthemums. It is atoxic, nonvolatile hydrocarbon related to kerosene. (09 Oct 1997) |
| pyretic | <medicine> Of or pertaining to fever; febrile. Origin: Gr. Burning heat, fever, from fire: cf. F. Pyretique. Source: Websters Dictionary (01 Mar 1998) |
| pyreto- | Fever. See: pyr-, pyro-. Origin: G. Pyretos, fever, fr. Pyr, fire (05 Mar 2000) |
| pyretogen | Rarely used term for pyrogen. Origin: pyreto-+ G. -gen, producing (05 Mar 2000) |