Emily Dickinson Lexicon

THUN'DER, n. [Sax. thunder, thunor; G. donner; D. donder; Sw. dunder; Dan. dundren; L. tonitru, from tono, to sound; Fr. tonnerre; It. tuono; Pers. ثُنْدُرْ thondor or thundur.]

1. The sound which follows an explosion of electricity or lightning; the report of a discharge of electrical fluid, that is, of its passage from one cloud to another, or from a cloud to the earth, or from the earth to a cloud. When this explosion is near to a person, the thunder is a rattling or clattering sound, and when distant, the sound is heavy and rumbling. The fact is in some degree the same with the report of a cannon. This sharpness or acuteness of the sound when near, and the rumbling murmur when distant, are the principal distinctions in thunder. [Thunder is not lightning, but the effect of it. See Johnson's Dictionary, under thunder.] There were thunders and lightnings. Exod. xix.
2. Thunder is used for lightning, or for a thunderbolt, either originally through ignorance, or by way of metaphor, or because the lightning and thunder are closely united. The revenging gods / 'Gainst parricides all the thunder bend. Shak.
3. Any loud noise; as, the thunder of cannon. Sons of thunder. Mark iii.
4. Denunciation published; as, the thunders of the Vatican.