a conventional term related to the god of thunder (lightning; more on the cult of storm and weather phenomena in ), perfect warrior and patron of the military social functions. His reconstructed name from the time of Proto-Indo-European society would sound as *Per(kw)un-; compare with ➚ Perun, ➚ Perkunas (Perkons, Perkuns/Parkuns), ➚ Pirwa, ➚ Piran, ➚ Fjörgyn, Thracian Hērōs Perkos or Perkōn(is?). Compare also with Greek Keraúnios “Thunderous” – agnomen of ➚ Zeus . Primarily Thunderer was related to the idea of fertility, through association with the beginning of the vegetation cycle (spring), rain and flora (mostly ➚ oak).
The importance of Thunderer increased in the time of Indo-European expansion. Then, the warrior features were ascribed to the past god of the sky (as Zeus and ➚ Jupiter, both theonyms literally mean “Sky”) or to the god of fertility (as ➚ Indra or ➚ Mars). In some cases it was the actual god of thunder (Perun, Perkunas, ➚ Thor, ➚ Donar, ➚ Taranis) who got aggrandized. In that time Thunderer became the protector, guardian and creator of cosmos, mostly as the victor over malevolent chaotic (chthonic) powers in the ➚ cosmogonic duel (see also SNAKE).
The god’s weapon was lightning, the prototype of all weapons (compare with Sanskrit vidyút “lightning, weapon”). It was primarily materialized in the form of stone (compare with Indra defeating his enemies with a stone avalanche; see Sanskrit áśman “stone; lightning strike; sky”, ádrivant “equipped with stones, armed with lightnings”). Sometimes it was hyperbolized to the mountain size, which is related to the idea on the sky made of stone (see SKY) or with the belief about the Thunderer residing on the mountain top: *Per(kw)un-. Compare this with Hittite perunaš and pirwa “rock”, Sanskrit párvata and Gothic faírguni “mountain”.
Gradually lightning-stone changed to:
– stone disc (see CHAKRA; compare with death of ➚ Phocus-2 and ➚ Acrisius),
– stone hammer (see MJÖLLNIR),
– oak club (see VAJRA),
– ➚ arrow (compare Polish strzałki gromowe “thunder arrows” – the fossilized rostra of belemnites; compare with Slovenian stréla “lightning, arrow”),
– axe (compare with Sanskrit kúliśa “axe; thunder arrow of Indra”)
– trident (its identity to lightning is confirmed by )
– and finally ➚ sword, sometimes recovered from (under) the rock (see THESEUS, compare with sword of King Arthur – Excalibur – probably from ex cal(cae) liber(are) “free from rock”) or from oak trunk (see SIGMUND).
Locally, Thunderer had many human hypostases:
– single: ➚ Heracles, ➚ Achilles (2), ➚ Diomedes (2), ➚ Perseus, ➚ Rama, ➚ Arjuna, ➚ Bhima (1), ➚ Cúchulainn , ➚ Rustam, ➚ Garshasp (1), ➚ Bijan, ➚ Mher (1 and 2), ➚ Sigurd, ➚ Beowulf, ➚ Ilya Muromets, ➚ Dobrynya Nikitych, ➚ Krak, ➚ Gish,
– and collective: ➚ Achaeans, ➚ Axsartagkata, ➚ Pandavas.
All of the abovementioned were the main characters of the heroic epics that followed the scenario of a cosmogonic duel.
Thunderer had the fourth day of the week dedicated to him:
– English Thursday and Old Icelandic thórsdagr (“Thor’s day”),
– Anglosaxon thunresdaeg (“Thunor’s day”; see DONAR) and German Donnerstag (“Donar’s day”),
– Latin Dies Iovis (“Jupiter’s day”) and from this French jeudi and Italian giovedi,
– Lithuanian Perkūno diena and Polabian Peräune dån (“Perkunas’ day”).
 P a u s., VIII, 29, 1;  Pa u s., V, 14, 7;  V a r r. fragm. 54.
C h. B l i n k e n b e r g, The Thunderweapon in Religion and Folklore, Cambridge 1911; E. S. M c C a r t n e y, Classical Weather Lore of Thunder and Lightning, “Classical Weekly” 25, 1931-1932; H . L ö m m e l, Der arische Kriegsgott, Frankfurt am Main 1939; H. L ö m m e l, Blitz und Donner in Rigveda, “Oriens” 8, 2, 1955; T. V. C i v ‘ j a n, Balkanskie dopolnenija k poslednim issledovanijam indoevropejskogo mifa o Gromoverzhce (in collective work) Balkanskij lingvisticheskij sbornik, Moskva 1977; W. S p e y e r, Die Zeugungskraft des himmlischen Feuers, “Antike und Abenland” 24, 1978.