Defn: The Pyrenees. Shak.

PYRENOID
Py*re"noid, n. Etym: [Gr. Pyrena, and -oid.] (Zoöl.)

Defn: A transparent body found in the chromatophores of certain
Infusoria.

PYRETHRIN
Pyr"eth*rin, n. Etym: [NL. Pyrethrum, generic name of feverfew, Gr.
(Chem.)

Defn: A substance resembling, and isomeric with, ordinary camphor, and extracted from the essential oil of feverfew; — called also Pyrethrum camphor.

PYRETHRINE
Pyr"eth*rine, n. (Chem.)

Defn: An alkaloid extracted from the root of the pellitory of Spain
(Anacyclus pyrethrum).

PYRETIC
Py*ret"ic, a. Etym: [Gr. pyrétique.] (Med.)

Defn: Of or pertaining to fever; febrile.

PYRETOLOGY
Pyr`e*tol"o*gy, n. Etym: [Gr. -logy: cf. F. pyrétologie.] (Med.)