The term has many different meanings to different people of different times, religions, and cultures.
I will speak of what the Buddha meant, because it is often misunderstood, and I like it. For the Buddha:
- The word "enlightenment" is a mistranslation. The proper meaning of Buddha is one who is Awake, and the word translated as "enlightenment" is Budh, which means living awake, having ones eyes open, seeing things as they are and not being deluded.
- In ancient Buddhism, Awakening is not freedom from everything. It is freedom, very specifically, from suffering. One who is awake does feel pain, say, during illness or at the loss of a loved one. But he or she is free of creating more pain than that - creating suffering through anxiety and worry, fear, anger, greed, avoidance, or any other kind of attachment or inappropriate relationship or connection to anything.
- Awakening is not a final goal. It is an early step in the process. Ideally, we Awaken after 6 months to 3 years of meditation practice, and then go on to live an Awakened life, perpetually deepening our freedom and joy, and helping others to let go of their suffering and live more joyful, peaceful lives.
I speak from the experience of deepening on this path for 30 years. I hope you will join me!