Isobront
Pronunciation : I"so*bront (i"so*bront)
Part of Speech : n.
Definition : Defn: An imaginary line, or a line on a chart, marking the simultaneous development of a thunderstorm, as noted by observing the time when the thunder is heard at different places.
[Iso- + Gr. bronth` thunder.] (Meteor.)
Source : Webster's Unabridged Dictionary, 1913