"All that we are is the result of what we have thought. If a man speaks or acts with an evil thought, pain follows him. If a man speaks or acts with a pure thought, happiness follows him, like a shadow that never leaves him."
True words from one of the greatest teachers we have ever known. The very act of attempting to describe what 'enlightenment' means immediately takes away from the reality of this state of being.
I can, however describe what it is NOT. It is not a perpetual body high, or feeling of being higher up than everyone else. This very thinking undermines the whole concept. It is not some closely guarded secret that requires ceremony, gifts, homage, sacrifice, etc... And finally, it is not attainable. Anyone actively 'searching', or looking to 'gain' enlightenment will never find it.
It is an inherent quality in every human. Enlightenment refers to 'ultimate knowing', or realizing the true nature of one's own life, the life around them, and the very world they live in. Everyone is brought in to this world already enlightened. As one grows older, this 'knowing' goes away once we learn how to function in this world. It can be likened to the analogy of the sun, Earth, and the clouds. Us humans are here on Earth, the sun is enlightenment, and the clouds are negative emotions, thoughts, opinions, prejudices, biases, etc... So the more aware someone is, the more clear & beautiful day they are having here on Earth.
One would think it would be wise to not have 'bad days', but it's another one of life's great illusions...one that we create for ourselves.