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The British military term, "Leftenant" , for an officer of Lieutenant grade.

I just watched the movie "Where Eagles Dare", starring Richard Burton and Clint Eastwood, and they seemingly used the word about a billion times.
So I looked it up, where multiple people explained the term :

https://www.theguardian.com/notesandqueries/query/0,5753,-19576,00.html

I liked the one guy's explanation:

Quote
The Brits are weird.

Basically, it's the same term for that military rank that existed for roughly a thousand years, but the letters and pronounciation have changed over the centuries. But some (or maybe many) in the British military still pronounce it as it originally was, or some approximation of it.