There was once a PhD defense in my university. The title was "special places on fields", but then in dutch. The auditorium was packed until they realized that it was about mathematics.
A math PhD candidate I know just told me that as he was first preparing for the language requirement for his candidacy, he came across the word 'corps' in the paper he was reading (in french) and was confused as to what a body had to do with math.
First time I saw the word "field" was when micromass used it somewhere.
I thought it was about some esoteric part of math that I never heard about.
It took some Googling before I realized that I did know it!