A term used to describe something, generally emotion, that is otherwise not describable. It can also be used in place of terms such as "brutal", "sick", and "savage". These terms are generally viewed as negative, but the impact of usage increases dramatically when used opposite of it's intended purpose.
Chemical (or chemmie for short) is a collective term to refer to artificially-synthesized drugs, in contrast to drugs that are consumed in a naturally-occurring form (e.g. weed, magic mushrooms and salvia).
MDMA, cocaine, ketamine, mephedrone and amphetamine are all considered chemicals.
Its when you have a really good chance at getting to something better with the opposite sex. Usually through just chatting. It sets the support for a much better relationship. Its when two people are just very much a like and a well made match.
Dude, you had a chemical connection with that guy!