Samadhi

Concentration, contemplation, absorption

A form of meditation widely practiced in Theravada Buddhism in which the mind is concentrated on a single object and gradually calmed until only the object is known. The ultimate goal of this meditation is to enter the state of samadhi which is when the distinction between the object and the meditator disappears, which is the realization of non-dualism. This state is a prerequisite to entering the four levels of jhana and enlightenment.

Superconscious state where there is no modification of the mind or Triputi.
NITYA

So, samadhi may refer to any of the highest levels of consciousness, in or out of trance. These states may be achieved by Yoga practice or by other means. It is the eighth and last stage of Yoga in Patanjali's analysis of yoga; most systems of Hatha Yoga likewise view samadhi as the state of ultimate achievement. In Buddhism, samadhi is the fourth and final stage of Dhyana or intense abstract meditation.
There are many levels of samadhi, which are given many different names. The lower forms of this absorption may be called saguna-samadhi (with attributes), savitarka-samadhi (with deliberation), savikalpa-samadhi (with change), savichara-samadhi (with reflection), sabija-samadhi (with seed), etc.
The higher forms of this absorption may be called nirguna-samadhi (without attributes), nirvitarka-samadhi (without deliberation), nirvikalpa-samadhi (without change or differences), nirvichara-samadhi (without reflection), nirbija-samadhi (without seed), etc.
Samadhi is the final of the eight stages given in Patanjali's analysis of the yoga systems.
"Samadhi is that same dhyana, when the object [of meditation] shines by it's own self, as if devoid [of form] or free [of the meditator]. (Yoga Sutras 3:3)