Trailokya (devanāgarī: त्रैलोक्य) or "triloka" is a Sanskrit term that can be translated as "three worlds" (or spheres, or planes of existence, or realms).
In Buddhist cosmology there are 31 planes of existence divided into three great divisions. Access from one plane to another is by two methods: by being reborn there in accordance with one's karma, or through the meditational practice. These realms have been described as follows:
The realms of existence are customarily divided into three distinct "worlds" (loka), listed here in descending order of refinement:
- The Immaterial World (arupa-loka). Consists of four realms that are accessible to those who pass away while meditating in the formless jhanas.
- The Fine-Material World (rupa-loka). Consists of sixteen realms whose inhabitants (the devas) experience extremely refined degrees of mental pleasure. These realms are accessible to those who have attained at least some level of jhana and who have thereby managed to (temporarily) suppress hatred and ill-will. They are said to possess extremely refined bodies of pure light. The highest of these realms, the Pure Abodes, are accessible only to those who have attained to "non-returning," the third stage of Awakening. The Fine-Material World and the Immaterial World together constitute the "heavens" (sagga).
- The Sensuous World (kama-loka). Consists of eleven realms in which experience — both pleasurable and not — is dominated by the five senses. Seven of these realms are favorable destinations, and include our own human realm as well as several realms occupied by devas. The lowest realms are the four "bad" destinations, which include the animal and hell realms.
All these are the worlds of post mortem states. For instance, Kâmalôka or Kâmadhâtu, the region of Mâra, is that which mediæval and modern Kabalists call the world of astral light, and the “world of shells”. Kâmalôka has, like every other region, its seven divisions, the lowest of which begins on earth or invisibly in its atmosphere; the six others ascend gradually, the highest being the abode of those who have died owing to accident, or suicide in a fit of temporary insanity, or were otherwise victims of external forces. It is a place where all those who have died before the end of the term allotted to them, and whose higher principles do not, therefore, go at once into Devachanic state--sleep a dreamless sweet sleep of oblivion, at the termination of which they are either reborn immediately, or pass gradually into the Devachanic state. Rûpadhâtu is the celestial world of form, or what we call Devâchân. . . the Esoteric Philosophy teaches that though for the Egos for the time being, everything or every one preserves its form (as in a dream), yet as Rûpadhâtu is a purely mental region, and a state, the Egos themselves have no form outside their own consciousness. Esotericism divides this “region” into seven Dhyânas, “regions”, or states of contemplation, which are not localities but mental representations of these. Arûpadhâtu: this “region” is again divided into seven Dhyânas, still more abstract and formless, for this “World” is without any form or desire whatever. It is the highest region of the post mortem Trailokya; and as it is the abode of those who are almost ready for Nirvâna, and is, in fact, the very threshold of the Nirvânic state, it stands to reason that in Arûpadhâtu (or Arûpavachara) there can be neither form nor sensation, nor any feeling connected with our three dimensional Universe.
- The Thirty-one Planes of Existence at Access to Insight.
- Helena Petrovna Blavatsky, The Theosophical Glossary (Krotona, CA: Theosophical Publishing House, 1973), 336-337.
- Triad at Theosopedia