A fanfiction in which several fandoms interact with one another.
Cross-overs largely involve time travel and interdimensional travel to meld two different fandoms.
I was confused when Dr. Gregory House was treating Harry Potter's illness, but I soon realized that I was merely reading a cross-over.
1. Generally performed by two males, the cross over involves the first male placing both hands inside his partner's pants - one over the buttocks, and one placed firmly over the groin. The male's partner returns this action, so that both arms cross over. This is typically performed in public, as a statement of pride in one's relationship. Experienced couples often resume walking while performing the cross-over, though this is a difficult technique and not recommended to beginners.
2. A dribbling technique used in basketball to change the dribbling direction quickly.
1. "Bob, we've been together for several months now...it's time we performed the cross-over."
2. "That's a brilliant cross-over by Kobe Bryant, he dumbfounded the other team there!"