synthetically or semisynthetically created drugs that are used rereationally. basically man made drugs created in a laboratory or some clandestine drug lab.
examples include lsd, mdma(ecstacy), methamphetamine, heroin, pcp, ketamine, several research chemicals (2ci, 2cb, 2ct7, DOM, DOB, DOI, 4-HO-DiPT, DiPT, 4-HO-mipt, several pcp analogues including pcc, pce, tcp, just to name a few), and finally various pharmaceutical drugs such as dxm, benzodiazepines, and various synthetic opiods including fentanyl, hydromorphone, oxymorphone, hydrocodone etc.
I quit using chems a long time ago. Now all i do is smoke weed, and indulge in the occasional mushroom trip.