The headword seems to be related to a series of words relating to orgiastic behavior and associated with the gods Dionysos and Pan ( LSJ entry at web address 1). Compare Hesychius beta6, 9, 10 epsilon1287 (cf. Latte 1.501-2); Lexica Segueriana 223.31 Bekker; Photius, Lexicon beta5, 6, 8; Etymologicum Magnum 183.45. Its only appearance outside lexicography is in the Doric vocative form βαβάκτα in a fragment of Cratinus (321 Kock, 22 Meineke, 359 Kassel/Austin), where it is an epithet of Pan. At Hesychius beta10 a possibly related word is identified as Lydian.
The gloss here is a word sparsely attested (two occurrences in an astrological work in a codex in Moscow: Catalogus Codicum Astrologorum Graecorum 12.178.17, 189.27), and in this case it seems likely to be a corruption of ὀρχηστής ('dancer') which appears in parallel entries (Hesychius beta6; Lex.Seg. 223.31 Bekker; Photius, Lexicon beta8), and which would have been nearly homophonous to ὀργιστής in late/Byzantine Greek. [Or perhaps ὀργιαστής (DW)?] On the other hand, the meaning 'raging person' would not be foreign to the orgiastic context: μανιώδης ('maniacal') is also used as a gloss in the lexica cited above). Adler notes Suda mss GIT and a corrector to ms V offer ὀρχηστής and related words as variant readings.