The more I thought about it, the more I thought that the word pericarditis sounded familiar, so I searched an electronic diary I used to keep and found this entry from January 3, 2008:
“I don’t remember the whole dream, just the very end, where I woke up with the word ‘pericardium’ in my brain. There’s nothing too peculiar about this except for one detail: I don’t remember ever hearing that word before in my life.”
“Later in the morning I looked it up online to see if I made it up, and it is indeed a real word. Even cooler is that it’s related to the chest/heart, where my niece hit me. Wikipedia says it is ‘a double-walled sac that contains the heart and the roots of the great vessels.’”
“I'm not saying that I've never heard this word before, only that I can't consciously recall hearing it before, and I had to try several spellings before I got it right. What I’m saying is that my conscious mind didn’t know the word, but my dreaming mind did.”
The dreaming mind and subconscious in general fascinates me.