Rosebud
This is it, guys. This is the big daddy of film symbols. Has it been parodied? Oh yes. Are people still writing articles about it? Oh yes. How about scholarly articles? Yep.
We open this movie by watching Charles Kane utter the word "rosebud" on his deathbed. Next thing you know, a room full of newsmen are asking what Kane meant by this word and what it can tell us about his life. As Mr. Rawlston asks the room, "Yes. Rosebud. Just that one word. But who is she?"
So here, based on the name, people tend to assume that Rosebud was a woman in Kane's past, someone he longed for in his final moments. Mr. Bernstein floats the same theory:
BERNSTEIN: That Rosebud, huh? Maybe, some girl? There were a lot of them back in the early days.
By the end of the movie, our central investigator Thompson has gotten no closer to finding out what "rosebud" means. But at least one other reporter can't help but think,
REPORTER: If you could have found out about what Rosebud meant, I bet that would've explained everything.
It's probably true that most audience members feel the same way, since we all want to know what Kane's tragedy "means" in a deeper sense. But Thompson muses by saying,
THOMPSON: Maybe Rosebud was something he couldn't get or something he lost.
But in the end, he doesn't think that figuring out "rosebud" would have brought anyone any closer to understanding Kane because people are way more complicated than that.
We only find out in the final scene of the movie that Rosebud is actually the sled that Kane used to play with as a child. It's also the last thing he was holding onto on the day Mr. Thatcher came to take him from his parents. In this sense, Rosebud symbolizes everything that Kane lost the day he moved away from home.
From that point on, his life was only ever about money and power, whether he knew it or not. And it's only at the end of his life that he can look back and recognize the exact point at which everything started to go so wrong.