The definition and meaning of mysticism have been the subject of debate for decades within academia. While in a colloquial sense its referent may be readily apparent, there is no one existing definition of the term that adequately captures the multiple, diverse phenomena that have been termed “mystical.” Genealogical studies reveal its origin in the Greek mystery religions (muo; mystikos), later taken up by the early Christian Fathers (mystical theology; mystical contemplation) to denote the effects of God’s presence as granted through grace and accessed through participation in a total religious matrix. Starting in the 17th century, one finds the beginning of the modern uses of the term as it became deracinated from a total religious matrix. In its new incarnation as a noun (la mystique), “mysticism” was utilized in the service of multiple academic methods designed to analyze religious phenomena. The implications of this trend were numerous: the democratization of mysticism, its rendering as an “experience” (e.g., William James’ pivotal analysis in The Varieties of Religious Experience), and its “modern” form as nontraditional or “unchurched” (e.g., the “spiritual but not religious movement”; “psycho-spiritualities”). In this latter sense, mysticism became linked to a cousin term, spirituality, which followed a parallel historical trajectory. The Western origins of the term evoked consternation from comparativists who accept using “mysticism” as a “term of art” only after shearing it from its theological echoes and possible orientalist and colonialist uses, further qualifying it relative to similar terms (e.g., moksha, nirvana, fana) as they accrue specificity in their particular socio-historical and religious contexts. This new, modern rendering of the term also gave rise to additional, sometimes incommensurate academic adventures (e.g., historians, theologians, philosophers, and a wide range of social scientists) into the “what” of mysticism. Such investigations have had the advantage of obviating the idealizations that may blind one to the more problematic formulations and implications regarding, for example, gender, sexuality, and race that can be found in tradition-based forms of mysticism. In turn, they helped facilitate the move to nontraditional forms of spirituality and mysticism while ushering in a new series of debates that currently occupy the field.