The term "mysticism" has Ancient Greek origins with various historically determined meanings. Derived from the Greek word μυω, meaning "to conceal", mysticism referred to the biblical liturgical, spiritual, and contemplative dimensions of early and medieval Christianity. During the early modern period, the definition of mysticism grew to include a broad range of beliefs and ideologies related to "extraordinary experiences and states of mind".
In modern times, "mysticism" has acquired a limited definition, with broad applications, as meaning the aim at the "union with the Absolute, the Infinite, or God". This limited definition has been applied to a wide range of religious traditions and practices, valuing "mystical experience" as a key element of mysticism.
Broadly defined, mysticism can be found in all religious traditions, from indigenous religions and folk religions like shamanism, to organised religions like the Abrahamic faiths and Indian religions, and modern spirituality, New Age and New Religious Movements.
Since the 1960s scholars have debated the merits of perennial and constructionist approaches in the scientific research of "mystical experiences". The perennial position is now "largely dismissed by scholars", most scholars using a contextual approach, which takes the cultural and historical context into consideration.
"Mysticism" is derived from the Greek μυω, meaning "I conceal", and its derivative μυστικός, mystikos, meaning 'an initiate'. The verb μυώ has received a quite different meaning in the Greek language, where it is still in use. The primary meanings it has are "induct" and "initiate". Secondary meanings include "introduce", "make someone aware of something", "train", "familiarize", "give first experience of something".