Pear \Pear\ (p[^a]r), n. [OE. pere, AS. peru, L. pirum: cf. F. poire. Cf. {Perry}.] (Bot.) The fleshy pome, or fruit, of a rosaceous tree ({Pyrus communis}), cultivated in many varieties in temperate climates; also, the tree which bears this fruit. See {Pear family}, below. [1913 Webster] {Pear blight}. (a) (Bot.) A name of two distinct diseases of pear trees, both causing a destruction of the branches, viz., that caused by a minute insect ({Xyleborus pyri}), and that caused by the freezing of the sap in winter. --A. J. Downing. (b) (Zo["o]l.) A very small beetle ({Xyleborus pyri}) whose larv[ae] bore in the twigs of pear trees and cause them to wither. {Pear family} (Bot.), a suborder of rosaceous plants ({Pome[ae]}), characterized by the calyx tube becoming fleshy in fruit, and, combined with the ovaries, forming a pome. It includes the apple, pear, quince, service berry, and hawthorn. {Pear gauge} (Physics), a kind of gauge for measuring the exhaustion of an air-pump receiver; -- so called because consisting in part of a pear-shaped glass vessel. {Pear shell} (Zo["o]l.), any marine gastropod shell of the genus {Pyrula}, native of tropical seas; -- so called from the shape. {Pear slug} (Zo["o]l.), the larva of a sawfly which is very injurious to the foliage of the pear tree. [1913 Webster] [1913 Webster]