Enlightenment (or brightening) broadly means the acquisition of new wisdom or understanding enabling clarity of perception. However, the English word covers two concepts which can be quite distinct: religious or spiritual enlightenment (German: Erleuchtung) and secular or intellectual enlightenment (German: Aufklärung). This can cause confusion, since those who claim intellectual enlightenment often reject spiritual concepts altogether.

In religious use, enlightenment is most closely associated with South and East Asian religious experience, being used to translate words such as (in Buddhism) Bodhi or satori, or (in Hinduism) moksha. The concept does also have parallels in the Abrahamic religions (in the Kabbalah tradition in Judaism, in Christian mysticism, and in the Sufi tradition of Islam).

In secular use, the concept refers mainly to the European intellectual movement known as the Age of Enlightenment, also called the Age of Reason referring to philosophical developments related to scientific rationality in the 17th and 18th centuries.

As per another emerging thought stream, "enlightenment", in conventional sense of complete realization, is impossible because "complete" is a state which never comes. The immediate next moment brings new beginning and may bring new truths as well. It may result in further requirement and scope of psychological and spiritual development beyond anything known till date.

Enlightenment in Buddhism

A Buddha, or fully enlightened one, is regarded as a sentient being who has developed all positive qualities, and has eradicated all negative qualities. According to the Theravada tradition, full enlightenment of a Buddha is not achievable for most; instead one strives to become an Arhat and achieve liberation from the cycle of uncontrolled rebirth and to achieve nirvana. This achievement is also called "enlightenment". In contrast, according to the Mahayana traditions, every sentient being is regarded as having the potential for achieving full enlightenment and Buddhahood.

Enlightenment in Zen

In Zen, Enlightenment is the state of being with no mind. It is the disappearance of the ego. It is the loss of all identification with the body and the mind. It is freedom from beliefs, opinions, ideals and concepts. It is always sudden, because it is not an achievement; it is already the case. It is a remembering. In Zen it is called the pathless path, that is, it is not something to be achieved, but it is to be Realized and lived. Meditation, with no thought, simply watching, watching the breath, is the initial method to create the space for its occurrence. There have been thousands of people who have been considered Enlightened Masters, such as Buddha, Bodhidharma, Lao Tzu, Osho, and it is seen as everyone's birthright.

Enlightenment in Indian Religions

In Indian religions (Hinduism, Jainism, Buddhism and Sikhism), Moksha (liberation) or Mukti (release) refers to liberation from the cycle of death and rebirth and all of the suffering and limitation of worldly existence. In Hindu philosophy, it is seen as a transcendence of phenomenal being, of any sense of material consciousness, time, space, and causation (karma). It is not seen as a soteriological goal in the same sense as in a Christian context, but signifies a dissolution of the material self to uncover the underlying, pure spirit: the undoing of conditioned mentality-materiality or nama-roopa (lit. name-form) to uncover one's eternal identity. Liberation is achieved by (and accompanied with) the complete stilling of all material passions — a state of being known as Nirvana.

Source: http://en.wikipedia.org/wiki/Spiritual_enlightenment
Source: http://en.wikipedia.org/wiki/Moksha

Author's Bio: 

An expert in Spiritual Growth, author, Hope Bradford CHT is an ordained minister, having practiced hypnosis and dream counseling
for over twenty years. Her areas of expertise, however, focus upon the more transpersonal aspects of hypnosis. These include trance processes facilitating one's intimate experience of the divine, for example: past life regression, spirit guide communication and chakra alignment.