Wiktionary
n. 1 (context physics English) A distribution of either electric charge or magnetization equivalent to two dipoles that point in opposite directions. 2 (context physics English) A magnet with two north poles and two south poles, used to focus a beam of particles.
Wikipedia
A quadrupole or quadrapole is one of a sequence of configurations of—for example—electric charge or current, or gravitational mass that can exist in ideal form, but it is usually just part of a multipole expansion of a more complex structure reflecting various orders of complexity.
Usage examples of "quadrupole".
I recall offhand, Tywood has published papers on the effect of liquid viscosity on the wings of the Rayleigh line, on higher-orbit field equations, and on spin-orbit coupling of two nucleons, but his main work is on quadrupole moments.