Mathieu Ricard:
«Enlightenment is a state of perfect knowledge or wisdom, combined with infinite compassion»
https://www.matthieuricard.org/en/blog/posts/what-does-buddhism-mean-by-enlightenment
Ajahn Amaro:
According to the Buddhist notion, a person is only completely healthy when he is completely enlightened (The Mind’s Own Physician ).
His Holiness the Dalai Lama:
The Dalai Lama once said, he does not know a living person who is completely enlightened (source unkown).
Conclusion:
None of the living persons the Dalai Lama knows is completely healthy.
There is no generally accepted scientific definition of “enlightement”.
I suppose there is a correlation between the Gamma wave activity in the left prefrontal cortex:
and first user report of how enlightened a person state he is or observers of the person state he is (unverified hypothesis of Peter Gamma, but difficult to verify or to disprove). The term enlightement is interesting and is often used in the meditation litterature, but not clearly defined over all meditation or spiritual traditions.