Gnosticism is a current in religion and philosophy characterized by the belief that there exists some mystical knowledge which holds the key to achieving some sort of enlightenment or power or transcendence or higher state of being. Buddhism and The Ultimate Comment very much fit in with this definition. Most Eastern religions are gnostic, while in the West there has been an equally rich gnostic tradition, but it has generally been heretical or occult. Christianity took some very weird forms in the first millenium, which are collectively called Gnosticism.
The Greek word 'gnosis' means knowledge, but direct, personal, intimate knowledge rather than propositional, intellectual knowledge. (In French, it would be 'connaitre' rather than 'savoir'.) Gnosis is a mystical, superconscious state in which the truths of the universe can be perceived directly. These are truths that cannot be expressed in language, because not every truth is a proposition. The Sufi use the word 'zawk' - taste - to describe this state. Gnosis is tasting reality. This is perhaps the best word, as it will be instantly understood that the 'taste' cannot be explained, communicated or arrived at intellectually - it must be experienced.
A gnostic state, in the usage of Peter Carroll and other writers on Chaos Magick, refers to a state of consciousness in which discursive, linear thought is switched off, allowing access to the occult power of the subconscious. One nearly universal aspect of magical techniques across times and cultures is that they have required a state in which ordinary thought is suspended, but awareness is heightened. What is required is that the mind be emptied of everything except the target of the Magick and to be aware of this with an unusual intensity. There are many ways of acheiving this. This usage is very different to the traditional meaning of the word.