glossolalia

Speaking a language one does not know, or speaking elaborate but apparently meaningless speech, while in a trance-like state (or, supposedly, under the influence of a deity or spirits); speaking in tongues.

[Adolf Bernhard Christoph] Hilgenfeld, indeed, is mistaken in explaining the unintelligibility of the γλω̑σσαι, only by the transcendent nature of what they expressed to the merely human consciousness; but he observes with great truth, that that which is common to prophecy and to glossolalia consisted in the exaltation of the consciousness above the merely human sphere, but that which is distinct consisted in this: that he who was prophetically inspired was in the full possession of his reflecting spiritual powers; […] [W]e showed that there is a human πνευ̑μα in a narrower sense, a capacity of immediate perception and insght. As all ecstasy, so also glossolalia was perfected in this πνευ̑μα: it was a miraculous agency of the Spirit of God […]

The occurrence in Acts ii. is therefore to be recognised, according to its historical import, as the phenomenon of the glossolalia, (not as a higher stage of it, in which the foreign languages supervened, Olshausen), which emerged for the first time in the Christian church, and that immediately on the effusion of the Spirit at Pentecost,—a phenomenon which, in the sphere of the marvellous to which it belongs, was elaborated and embellished by legend into a speaking in foreign languages, and accordingly into an occurrence quite unique, not indeed as to substance, but as to mode[…], and far surpassing the subsequently frequent and well-known glossolalia, having in fact no parallel in the further history of the church.

Synonym of xenoglossy (“knowledge of a language one has never learned”).

As he indicated in the subtitle of his study, [Olivier] Flournoy regarded [Hélène] Smith's Martian as a kind of "glossolalia." In this category, he also included her "Hindu," "Ultra-Martian," and the other extraterrestrial tongues that she would later speak.