Q: I heard you on the radio discussing the expression “his name is mud.” I did some research online and it seems that Dr. Samuel Mudd was the man who mended John Wilkes Booth’s leg and this is where the expression comes from. Just thought I’d let you know.
A: Thanks for the information on Dr. Mudd, but he isn’t the origin of the phrase. According to the Oxford English Dictionary, the noun “mud,” meaning a stupid (thick) fellow, dates back to 1708, and the expression “his name is mud” dates back to 1823. Booth shot Lincoln in 1865.
So, it isn’t true that Dr. Mudd’s example inspired the expression, although that explanation has been widely disseminated on the Internet.