An aura. An energy. A place in time. That which is all around you. Can be used to describe most anything, from them poisonous chemicals to an anomoly of nature - up to and including a stringy, stinky hairpiece purchased from Morrie. not possible to live a day without experiencing Koehl in some form and tense. Usually refers to weed smoked in any form.
"let's do a Koehl."
"Daniel LaRusso fucks Koehl up in Karate Kid."