In the Buddhist sense enlightenment means achieving absolute spiritual realization through loss of the ego and, ultimately, one’s individuality. Once enlightened the Buddhist believes they’re no longer reborn and, and through the annihilation of any kind of individuality, even spiritual individuality, they apparently free themselves from suffering.
A spiritual meaning for the word enlightenment is not restricted to Buddhism, however. The Oxford English Dictionary tells us that, as far back as 1621, enlightenment has been used in Christianity to refer to the idea that God illuminates individual souls and that such souls are powerless to illuminate themselves with divine grace and understanding.
1621 R. Aylett Song of Songs i. iv. iv. 83 The Word, without the Spirits enlightenment, Is as good Seede sowne on vntilled ground.¹
In the historical sense the period of “The Enlightenment” refers to an 18th-century philosophical movement emerging out of the 17th-century Scientific Revolution, to include the works of Adam Smith, Locke, Hume and Newton. It advocated reason and education over what was regarded as superstition, blind faith and historically laden dogmas. So in this context, the word enlightenment has a totally different meaning than the quotation above.
1836 N. Amer. Rev. July 176 When he [sc. Tieck] made his first appearance, it was, under the banner of Nicolai, as one of the Berlin advocates of enlightenment and reason, and enemies of superstition and mysticism.²
The Enlightenment championed the idea of “progress” as a challenge to entrenched forms of Christianity; however the idea of progress, and all the unspoken connotations that go with it, is now questioned by many. In France the Enlightenment produced the first great encyclopedias of Diderot and d’Alembert, with contributions from leading figures like Voltaire, Montesquieu, Condorcet and Rousseau.
In the Western contemporary sense enlightenment means a novel thought, a new way of looking at things, insight or the dispelling of ignorance.
¹ OED third edition, November 2010; online version March 2012. <http://www.oed.com.ezproxy.torontopubliclibrary.ca/view/Entry/62448>; accessed 01 May 2012. An entry for this word was first included in New English Dictionary, 1891.