thunderstorm

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A transient, sometimes violent storm of thunder and lightning, often accompanied by rain and sometimes hail.

Century Dictionary and Cyclopedia

1. n. A storm accompanied by lightning and thunder, occurring when the atmosphere is in a state of unstable equilibrium, and has a high relative humidity. Thunder-storms have been conveniently classified into heat thunder-storms and cyclonic thunder-storms. The former is the type preëminently characteristic of the equatorial regions, where lightning and thunder occur on their grandest and most violent scale. Here the thunderstorm has little or no progressive motion, and its entire history may be followed in the overturning process by which an abnormally hot, humid, unstable condition of the atmosphere becomes stable. In summer similar heat thunderstorms arise locally in temperate latitudes, especially in hilly or mountainous countries. Thunder-storms of the second class are associated with areas of low pressure, and are found most frequently on their southern border, in the quadrant where an unstable atmospheric condition tends to prevail. These thunder-storms have a progressive motion eastward, but their velocity may be quite different from that of the general cyclonic movement with which they are associated. The different isobaric types known as secondaries and V-shaped depressions give rise to thunder-storms having distinct features, and those accompanying the latter have been specifically designated line thunder-storms. In general, the diurnal and annual periods and other characteristics of cyclonic thunder-storms exhibit a wide diversity in different regions, and thereby illustrate the intimate dependence of these storms on the differing cyclonic conditions which characterize different climates. Thus, in Iceland thunder-storms occur only in winter, so that the usual annual periodicity is there reversed.

Wiktionary

1. n. A storm consisting of thunder and lightning produced by a cumulonimbus, usually accompanied with rain or hail. A more severe thunderstorm can cause mesocyclones.

GNU Webster's 1913

1. n. A storm accompanied with lightning and thunder.

WordNet 3.0

1. n. a storm resulting from strong rising air currents; heavy rain or hail along with thunder and lightning