For a long time, I used to use the word "Enlightenment" to refer to the state of egodeath and permanent Realization of the state of nonduality and
Historically, it is better used to designate the 18th century historical movement involving the rise of reason and science in 18th century England, France, Scotland, and other countries which was the beginning of secular Modernity.
Etymologically, it is a very poor translation of the Buddhist term bodhi or sambodhi ("Complete Awakening"), and equivalent Vedantic terms like jnana and moksha.
Finally, and most importantly, in the whole New Age/New Paradigm/Postmaterialism/Cultural Creative/Translucent/Integral movement or revolution, no word has been so abused by self-deluded pretenders and con-artist imposters who try to pass themselves off as "Enlightened beings", as Gurus, and so on. Many of these individuals - even sincere ones - seem to lack even simple or common gnosis, with some the power goes to their head (because really they are no more spiritually advanced than you and I, often from they would appear from their actions obviously much less advanced, go on to become "abusive gurus" (who are not true gurus at all, but self-indulgent narcissistics lacking true empathy). These abusive gurus, as well as the sincere but self deluded types, and those who are sincere and rationalise or justify their abuse or weakness by thinking they are helping others when they are abusing them, all have a little bit of knowledge, the sort anyone can pick up from any simple book on Vedanta or Theosophy or even New Age pop-esotericism. This, combined with a powerful charisma, strong or domineering personality, and the tendency of certain weak or masochistic people to choose someone who will dominate or punish them, is easily able to explain the proliferation of these so-called "Enlightened" teachers. And even among the most sincere, non-absuive types there has been a failure to deliver the goods or atatin any authentic state, which led one author to instead coin the term "Translucent"
Here instead of Enlightenment I will use the capitalised (to distinguish from the usual sense of the word) term "Realization" to refer to the authentic state of what those who claim to be Enlightened only pretend to be at.
But because the Kheper site is very large, and it takes a while for me to revise everything, the word "Enlightenment" will still appear on the site for some time. In these cases however the link will still point to the Realization pages here.