||Hys`te*re"sis (?), n. [NL., fr. Gr. &?; to be behind, to lag.] (Physics) A lagging or retardation of the effect, when the forces acting upon a body are changed, as if from velocity or internal friction; a temporary resistance to change from a condition previously induced, observed in magnetism, thermoelectricity, etc., on reversal of polarity.

• a characteristic property or behavior of a system that has some time lag or delay, of being history-dependent, or of having a material property that follows a closed loop when plotted; specifically the response "Y" takes a different value for an increasing input "X" than for a decreasing "X"