The definition of "kosher". The question was from a random stranger in the grocery store. We were both buying spices, she had a bottle in her hand and asked "What does kozher mean?" I looked at the bottle, said "Oh, kosher. Legal under Jewish dietary laws." I don't know what she selected.
To be fair, a lot of people who aren't Jewish and haven't lived in areas with much of a Jewish population wouldn't necessarily know what that means, either - may have heard the term, perhaps, but not be able to define it. I'm not sure I could tell you exactly what *does* go into making something kosher (or kosher for Passover specifically) - I know it has to do with ingredients and with a rabbi inspecting the facility, but I couldn't tell you the nuances of what that involved.
My only knowledge of the word was as kosher salt until I was in my 20s.
In the UK, especially in London (where the largest Jewish population is), kosher often gets used to mean legal or legitimate, in proper order. There was an episode of The Apprentice UK where one of the candidates was asked to find a kosher chicken, and had only heard of the word in that context. I don't know what on earth she thought a legal chicken looked like!