'Samadhi' is a meditative state of spiritual life when the meditator and the meditated combine. At this point, there is no thought process. This is considered to be the highest meditation level and the strongest state of a relaxed mind.In renunciation and forbearance and patient bearing of all the burdens of spiritual life, the Upanishads allow one to refrain from wasteful action, restraint of voice, body , and mind, until one can attain samadhi.
'Samadhi' is also the highest concentration level, where the focused object and the concentrated individual become one.In this state of meditation, it absolutely eliminates the distinction between one's self and the object being meditated upon.
One can only attain one's true nature through samadhi, the Atman. One that attain samadhi by following the various stages of the raja yoga or psychic control process. Only by doing selfless behavior as envisaged in karma yoga one can attain samadhi. So does bhakti and jnana yoga.
The mind is so engrossed with the meditation topic in samadhi that nothing else is remembered. Samadhi also means going beyond the three consciousness stages of awakening, dreaming, and sleeping. In the samadhi state, the ego is lost entirely. The soul then ceases to exist and is transformed into a world beyond the soul and the ego in which the self loses its consciousness.
Samadhi can be called a state beyond thought, beyond consciousness, and beyond thinking.The body halts its metabolic activities almost entirely, but the individual doesn't die. In that state, there is no thinking, but the person returns as a person with full and uninterrupted clarity of mind and a very simple worldview.