STUMPERS CCCIV

I'm thinking of a five-letter word. Drop B and re-arrange the letters, you get a pair of four-letter anagrams. Drop an E and re-arrange the letters, you get a second pair of four-letter anagrams. Drop an R and re-arrange the letters, and you get a third pair of four-letter anagrams. If you drop a different letter from this word, you are left with a seventh four-letter word. What is the original word, what are the three pairs of anagrams, and what is the seventh word?

HINTS:
1. The word has been adopted into English from a foreign language.
2. The word has to do with money.
3. The seventh word is a slang/colloquial term.

Answer:

The word is RUBLE.

Drop the B: RULE - LURE
Drop the E: BLUR - BURL
Drop the R: BLUE - LUBE
Seventh word: Drop the L: RUBE