The Collaborative International Dictionary of English v.0.48:

Hysteresis \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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hysteresis
    n 1: the lagging of an effect behind its cause; especially the
         phenomenon in which the magnetic induction of a
         ferromagnetic material lags behind the changing magnetic
         field

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "hysteresis":
   dead time, diamagnetism, electromagnetism, ferromagnetism, gain,
   gilbert, holdup, hysteresis curve, lag, magnetic circuit,
   magnetic conductivity, magnetic creeping, magnetic curves,
   magnetic dip, magnetic elements, magnetic figures, magnetic flux,
   magnetic friction, magnetic hysteresis, magnetic lag,
   magnetic moment, magnetic permeability, magnetic potential,
   magnetic remanence, magnetic variation, magnetic viscosity,
   magnetics, magnetism, magnetization, maxwell, output lag,
   paramagnetism, permeability, process lag, residual magnetism,
   throughput, time constants, time lead, weber