The state achieved during the use of drugs, mainly psychoactives such as opiates, marijuana, benzodiazepines, etc. These drugs generally bring about a feeling that everything is 'glowing'; an intense and calming sensation that you are intimately connected to your surroundings, i.e. your living space, friends, loved ones, animals, etc.
After the dose I had at the Phil and Friends show, I was glowing. Everything connected to me. Reciprocity and symbiotic connections abound.
A collective sub-culture of 'deadicated' fans of the American psychedelic/jam/rock band the Grateful Dead.
Look at all the traffic, Jill. Oh, there's that festival this weekend. Must be all the deadheads passing through.