Other forms: revelations
Discovering that you had a long-lost sister would definitely be a revelation, or a surprising realization. Finding out she had been living in the house next door for years would be an even more startling revelation!
It is not a surprise that the word revelation is related to the word reveal, because revealing is the action of showing something that was previously covered up or unknown. You can even use both words in the same sentence: "You might find it a revelation if someone revealed to you that your house was sitting on top of a gold mine!"
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