Complex sentence: The term Mixolydian was originally used to designate one of the traditional "harmoniai" of Greek theory, and it was appropriated (along with six others) by 2nd-century theorist Ptolemy to designate his seven "tonoi" or transposition keys.
Split into simpler sentences: The term Mixolydian was originally used to designate one of the traditional "harmoniai" of Greek theory. It was appropriated later (along with six other names) by 2nd-century theorist Ptolemy to designate his seven "tonoi" or transposition keys.