The transpersonal is a term used by different schools of philosophy and psychology in order to describe experiences and worldviews that extend beyond the personal level of the psyche, and beyond mundane worldly events.
Definition and context
The transpersonal has been defined as experiences "in which the sense of identity or self extends beyond (trans) the individual or personal to encompass wider aspects of humankind, life, psyche or cosmos".  The field of Transpersonal Psychiatry has defined the term as "development beyond conventional, personal or individual levels."  One of the founders of the field of transpersonal psychology, Stanislav Grof, has defined transpersonal states of awareness as such: "The common denominator of this otherwise rich and ramified group of phenomena is the feeling of the individual that his consciousness expanded beyond the usual ego boundaries and the limitations of time and space."
The term is related to the terminology of peak experience, altered states of consciousness, and spiritual experiences.  Note a The term is also associated with psychedelic work, and psychotechnologies, that includes research with psychedelic plants and chemicals such as LSD, ibogaine, ketamine, peyote, ayahuasca and the vast variety of substances available to all human cultures throughout history.Note b
Origin of the term
The term has an early precedent in the writing of philosopher William James, who used the term "Trans-personal" in one of his lectures from 1905.  However, this early terminology, introduced by James, had a different meaning than the current one  and its context was philosophy, not psychology,  which is where the term is mostly used these days.
There has also been some speculation of an early precedent of the term in the writings of Carl Jung, as a result of the work of Jung's translators. It regards the jungian term ueberpersonlich, used by Jung in a paper from 1917, which in later english translations appeared as superpersonal, and later, transpersonal. Note c In a later, revised version, of the Psychology of the Unconscious (1942) there was even a chapter heading called The Personal and the Collective (or Transpersonal) Unconscious. 
However, the origin of the term transpersonal, as it is currently used in academic writing, is mostly associated with the human potential movement of the 1960s and the founders of the field of Transpersonal Psychology; Anthony Sutich, Abraham Maslow and Stanislav Grof.  According to Vich  all three had used the term as early as 1967, in order to describe new ideas in the field of Psychology. In 1968 the term was selected by the founding editors of the Journal of Transpersonal Psychology, Abraham Maslow and Anthony Sutich, in order to represent a new area of psychological inquiry. Note d According to Powers  the term “transpersonal” starts to show up in academic journals from 1970 and onwards.
Transpersonal schools and orientations
The philosophy of William James, the school of Psychosynthesis (founded by Roberto Assagioli), and the Analytical school of Carl Jung are often considered to be forerunners to the establishment of transpersonal theory. Contemporary schools that have a distinct transpersonal perspective include Transpersonal psychology, Transpersonal anthropology and Transpersonal ecology. Other academic orientations, whose main focus lies elsewhere, but that are associated with a transpersonal perspective, include Humanistic psychology and Near-Death Studies. 
- a. Grabovac & Ganesan, 2003: Table 3.
- b. See Winkelman & Roberts, 2007: "Part III. Transpersonal Dimensions of Healing with Psychedelic States"
- c. John Beebe, San Francisco Jung Institute Library Journal
- d. The term was considered to be an improvent upon an earlier term called «transhumanistic». 
- Walsh, R. and F. Vaughan. "On transpersonal definitions". Journal of Transpersonal Psychology. Vol. 25, No2, pp. 199-207, 1993.
- Scotton, Bruce W. "Introduction and Definition of Transpersonal Psychiatry". In Scotton, Bruce W., Chinen, Allan B. and Battista, John R., Eds. (1996) Textbook of Transpersonal Psychiatry and Psychology. New York: Basic Books.
- Grof, Stanislav. (1975, 1993). Realms of the Human Unconscious: Observations from LSD Research. New York: Viking, London: Souvenir Press.
- Miller, John J. "Book Review: Textbook of Transpersonal Psychiatry and Psychology". Psychiatric Services 49:541-542, April 1998. American Psychiatric Association
- Grabovac, Andrea D. & Ganesan, Soma. "Spirituality and Religion in Canadian Psychiatric Residency Training". Canadian Journal of Psychiatry, Vol 48, No 3, April 2003
- Vich, M.A. (1988) "Some historical sources of the term 'Transpersonal' ". Journal of Transpersonal Psychology, 20 (2) 107-110
- Freeman, Anthony. "A Daniel Come To Judgement? Dennett and the Revisioning of Transpersonal Theory". Journal of Consciousness Studies, 13, No. 3, 2006, pp. 95–109
- Lukoff, David and Lu, Francis. A Transpersonal-Integrative Approach to Spiritually Oriented Psychotherapy, in L. Sperry and E. P. Shafranske (2005) Spiritually Oriented Psychotherapy, American Psychological Association.
- Judy, Dwight. Transpersonal psychology: Coming of age. ReVision, 02756935, Winter94, Vol. 16, Issue 3.
- Ferrer, J. N. (2002). "Revisioning transpersonal theory: A participatory vision of human spirituality". Albany,NY: State University of New York Press.
- Powers, Robin. "Counseling and Spirituality: A Historical Review". Counseling and Values, Apr 2005, Vol.49(3), pp.217-225.
- Scotton, B.W., Chinen, A.B. and Battista, J.R. (ed. 1996), Textbook of Transpersonal Psychiatry and Psychology. New York: Basic Books.