There are RC opioids although most of them are not more common for good reasons, usually they are unfit for recreational purposes as many of the RC opioids that I've found looked to be incredibly dangerous for human consumption due to bring extremely potent and basically the risk vs reward ratio is sooo much risk for sooo little reward and IMO that's why RC opioids aren't a bigger thing.
There was o-desmethyltramadol which was cool and actually became popular, but all the others I've seen have really obscure names because they havent been used enough for people to even consider naming them, most ive seen were active in micrograms and thus aren't commonplace because more than half of the people that would want to buy RC opioids don't have the proper measuring equipment / scales or the willpower to stay safe when using extremely potent opioids while having bulk amounts in supply.
BTW, the word for something that mimics an opiate is opioid.