From the site thefreedictionary.com to roleplay is "to assume or represent in a drama; act out" & "to assume or act out a particular role."
Let's chop the definition down into simpler means.
Okay, first and foremost, don't be stupid. The drama mentioned there is not to be taken literally. Be wise. Words don't mean the exact same thing as what your mind had thought. That's why there are such things as words meant as a connotation AND a denotation. For those youngsters who haven't taken up this topic on their English classes, let me share with you what I have learned with regards to words meant as a connation and a denotation. The easiest word to for such example is . , as a noun, is orginally denoted as the condition of being either a male or a female - depending on which ual organ you have, and if a hermaphrodite, depending on organ is more active. But why is as the act of having ual had initially popped on my mind [[DON'T DENY IT. I DID TOO. XD]]? Because the here that your mind had processed is the connotative meaning of what should mean. So , as a noun, in relation to its connotative meaning is the ual activity.
So going back to the drama mentioned from the dictionary, it doesn't mean that that drama should mean the climatic events from a series of movies, shows, etc. for exmple, breakup between couples, an epic drama comes in such as fights, bitter moments, and suches. It would simply mean "play". PERIOD.
Reconstructing what the dictionary has given, roleplay is to assume or represent in a PLAY.
A big check now that we've taken down the first definition.
Secondly, let's take up the follow up definition from the first which is act out. From the words themselves, act out. Should I go into details here? Well, I should in case some people would need help. Let's define them from the dictionary that I have mentioned awhile ago, according to its thesaurus, act out is "represent an incident, state, or emotion by action, especially on stage. Scratch especially on stage since we're dealing with a site not a program here. By the definition itself, you would clearly and undeniably notice how the first and second correlate each other and how they mean as the same.
Another check as we are able to take down the second defintion.
Lastly, is to assume or act out a particular role. Same with the second but this one is mentioned in definite. But to further explain this, it is when you put yourself in a character's shoes and act as if you are that character. ACT not be who you are.