Very often in common usage words mean the opposite of their actual meaning.
One example is the biblical term decimate. Herod had one in ten killed, but through centuries of misuse it has come mean nine out fo ten, or near total destruction.
Another word in this catergory is sophisticated. The philosopher sophocles was renowned for clever but false arguments. ( proving two plus two equals five for instance), and this is what the word meant and came from, overly or unecessarily complicated. Nowadays it means stlylish and clever.(not unlike myself)