Samadhi is Sanskrit and is usually translated as concentration but it is a high degree of concentration, one-pointedness, that is often experienced as spiritual bliss. Every meditator eventually experiences it except those who meditate while ignoring the precepts and the third, fourth and fifth folds of the eightfold path. Samadhi is called kensho in Japanese.
Having a samadhi experience doesn’t mean that we have attained enlightenment.
There are many different levels of samadhi. The experience may be brief in time or lengthy. It may be deep or shallow.
Master Hsuan Hua was meditating one night in a hut he built by his mother’s grave as an exercise in filial piety. A bright light shot out of the hut and the townspeople grabbed buckets of water and ran to the cemetery to douse what they thought was a fire. The hut was ablaze with light when they arrived. The Master was sitting inside, in samadhi, emitting light. There was no fire.
Sitting in meditation in Taipei, Taiwan in August, 1979, I heard a beautiful flute playing. A window was open and I was certain that a musician was in the street. I got out of my posture and looked out the window, but no flute player was there; just the usual street scene.
I then realized that I had heard the flute of Krishna of which our Hindu friends speak. Still in a meditative mood, I sat back down, certain that the music would return and it did.
I listened to it for awhile, and it was beautiful. I will remember this sublime, unforgettable tune forever, I thought. And I will record it and Paul McCartney, eat your heart out! I’m going to be rich!
Need I add that the music stopped and I can’t recall a single note of it?
Zen masters have a colorful term for a samadhi experienced in the absence of wisdom: they call it Dead Tree Samadhi.