PERIOD, in numbers, is applied to the recurring part of a circulating decimal.
PERIOECI (περίοικοι) is an old geographical term used to denote those who dwelt under the same latitudes but under opposite longitudes, just as antaei (ἀνταίοι) meant those under the same longitude but opposite latitudes, and antipodes (ἀντίποδες) those under opposite latitudes and opposite longitudes.
PERIPATETICS (περιπατεῖς, I walk about), a term applied to the disciples of Aristotle, because he taught them while walking in the περὶπατος, or promenade of the Lyceum at Athens. Peripatetic accordingly came to be equivalent to Aristotelian. (See ARISTOTLE, and ARISTOTELIAN PHILOSOPHY.)
PERIPHERY (περιφέρω, I carry round) signifies, according to the Greek use of the term, the circumference of a circle. It is usually applied, however, by the moderns both to rectilinear and to curvilinear figures.
PERIPHRASIS (περί, about, φράζω, I speak) signifies properly circumlocution, and is applied to that figure of rhetoric in which more words are used than are necessary to express the idea, with the design of avoiding common and trite modes of expression, and thus giving dignity and elevation to the discourse. The periphrasis is of great use on some occasions; and it is often necessary, to make things be conceived which it is not proper to name. It is sometimes polite to suppress the names, and only to intimate or allude to them. These turns of expression are also particularly serviceable in oratory; for the sublime admitting of no direct citations, there must be a compass taken to insinuate the authors whose authority is borrowed. A periphrasis, by turning round a proper name in order to make it understood, amplifies and raises the discourse; but care must be taken that it be not too much swelled nor extended mal à propos, in which case it becomes flat and languid.
PERIPNEUMONY (περί, about, πνεύμων, the lungs) signifies properly an inflammation of the substance of the lungs, as distinguished from pleurisy, or the inflammation of the membrane which invests the lungs.
PERISTALTIC (περιστάλλω, I involve) is an epithet given to a vermicular spontaneous motion of the intestines, performed by the contraction of the circular and longitudinal fibres of which the fleshy coats of the intestines are composed; by means of which the food, chyme, chyle, faeces, &c., are kept moving towards the termination of the alimentary canal.