A person who has what is known as “the gift of tongues” is usually in the midst of religious ecstasy, trance, or delirium. The speaker — and often witnesses too — believe that they are being possessed by a supernatural spirit or channeling the language of a deity or divine being.
Experts call this phenomenon glossolalia, a Greek compound of the words glossa, meaning “tongue” or “language,” and lalein, meaning “to talk.”
Speaking in tongues occurred in ancient Greek religion. It is also mentioned in the The Act of the Apostles in the New Testament, which says that it first occurred among followers of Jesus at Pentecost. The gift of tongues then reappeared when a follower was converted to Christianity. Today, it is commonly associated with Pentecostalism.
Xenoglossy is often mistakenly used to refer to tongue-speakers. However, xenoglossy is a paranormal phenomenon in which a person is able to speak a language that he or she has never heard, read, or been exposed to in any way.
For example, a person who shows signs of xenoglossy might fluently speak Japanese despite having never studied the language, visited Japan, or been exposed to Japanese songs, television shows, web sites, etc. It is a phenomenon that is not generally accepted by linguists and psychologists.