Speaking in tongues, also known as glossolalia (Greek: γλωσσολαλία), is an activity or practice in which people utter words or speech-like sounds, often thought by believers to be languages unknown to the speaker. One definition used by linguists is the fluid vocalizing of speech-like syllables that lack any readily comprehended meaning. In some cases, as part of religious practice, some believe it to be a divine language unknown to the speaker. Glossolalia is practiced in Pentecostal and charismatic Christianity as well as in other religions.