Examples:
John...Jack
William...Bill
About 15 years ago, I had a coworker named Robert who since he had been in elementary school had always wondered why Bob was the nickname for Robert. Of course, from a young age, he had already educated himself on the recorded origins of how it happened, but that still did not satisfy his burning desire to understand it better. I have known many men named Robert who were known by nicknames of Bob or Bobby, and many women named Roberta who were known by the nickname Bobbie, and it never occurred to me until I met the man alluded to above that such a dichotomy might exist.
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