Here are a few words and definitions that are commonly used when discussing meditation, spiritual truth seeking, and psychic phenomena related to the path of non-duality:
Absolute samadhi: a state of mind in which there is pure non-conceptual awareness without any sense of being a separate observer (selfhood disappears). Zen describes this state as "the falling off of mind and body." Awareness is present, but there is no content of awareness, and therefore nothing can be known of, or said about, this state. This state is usually preceded by "the off sensation," a kind of skin-surface numbness that spreads over the hands, arms, shoulders, face, and head. It feels a bit like sinking to the bottom of deep sea and sitting there motionless while remaining highly aware. It has also been described as a feeling of becoming grdually solidified into a block of ice, and there is a distinct sense of coolness associated with it. Thoughts generally do not occur in samadhi. If more than one or two thoughts arise in close proximty, duality generally reappears, and it feels as if one "thaws out" in slow motion. Absolute samadhi usually occurs during sitting meditation when the body is still (little proprioceptive feedback), and usually involves some degree of breath regulation (diaphragmatic breathing rather than chest breathing).
Relative samadhi: a state of mind in which mind and body are unified in the midst of physical activity, but in which the ordinary sense of time, space, and selfhood is absent. The world is seen and responded to, but cognition is absent. This state is sometimes called "flow" or "being in the zone." Reflectivity is not extant.
Kensho: Zen writers describe kensho as "the experience of seeing into one's true nature." If minor, it is equivalent to what most people would call "an epiphany;" if major, it is what people would call "an experience of cosmic consciousness," or "oneness." The universe is perceived as infinite, unified, alive, intelligent, and whole.
Satori: Sometimes called "enlightenment," satori is the realization that the one seeking enlightenment does not exist and has never existed. Selfhood is seen to be an illusion created and sustained by thoughts. An individual realizes that she is not who she thought she was, and that who she is is what remains after the illusion is seen through. In short, she does not see who she is; she sees who she is not.
Kriya: Muscle jerks, spasms, and rippling precipitated by meditation.
Photistic experiences: There is a particular word for this (please fill in the blank if you know it_____________, but it manifests as flashes of intense bright light sometimes precipitated by meditation, and includes other light-related phenomena
There is also a word for aural experiences precipitated by meditation. These can include explosive sounds, voices, etc.
Universal sound: There may be a specific word for this, but it is the dull "seashell-like" roaring or ringing in the ears that is always present behind all other sounds. Most meditators can hear this sound any time they turn their attention to it.
Non-locality experiences: Psychic or physical experiences that defy common scientific explanation, and make sense only from the perspective that reality is inherently unified, and real separateness is illusory
Sunyata: a word that Buddhists use for emptiness, or the interpenetration of form and void.
Koan: Any existential question that cannot be answered using the intellect. The Rinzai Zen Sect utilizes about 1800 formal koans which are used for contemplation and deepening one's understanding, and also as a way of testing a student's existential understanding.
An experience: the act of living through an event or events; personal involvement in or observations of events as they occur. An experience has duration.
A realization: to make real or understand fully, A realization occurs instantly and has no duration.
Kundalini: Enigma is probably best qualified to write about this.
Chakras: Top and Enigma may both have input concerning these.
Chi: the electrical energy field that circulates through the body. This is a major factor in Chinese medicine and is utilized by acupuncturists.