Explain the shared quality of these words: Monopoly, Decimate, Octopus, Divide, Tribune, Quarter?

Please help me decipher what these words have in common. What do they all have in common? ANY AND ALL ANSWERS AND GUESSES are welcomed and appreciated. I am especially looking for something that has to do with the English language, such as grammar, parts of speech, ways that these words can be used in a sentence, ways that these words can be changed, idioms, etc.