Where does the word “nemesis” come from and What does nemesis mean?

Not all of the Greek gods were kindly.

There was one, according to mythology, whose duty it was to sit in judgment upon men. Her name was Nemesis, thought to have been the daughter of Night.

She measured out happiness and unhappiness, and saw to it that any who were too greatly or too frequently blessed by fortune were visited in equal measure by loss or suffering.

From this last she became looked upon as the goddess of retribution, as a goddess of vengeance and punishment.