Opioids are things that act on the opiate receptors, mostly the mu and delta ones. They shouldn't be confused with opiates, or poppy alkaloids.
There is a handy chart available for you to convert dosages around.
 Common Opioids
- Morphine - MS Contin etc
- Diacetylmorphine - Heroin, everyone's favourite
- Codeine - Tylenol 1, 2, 3
- Hydrocodone - Vicodin
- Oxycodone - Percocet, OxyContin
- Miosis (shrunken pupil)