The term 'Philosophers' Group' refers to the group of ancient Greek philosophers known as the 'Presocratic Philosophers'. This group of thinkers, which included Thales, Anaximander, and Heraclitus, were the first to attempt to explain the world through naturalistic means rather than relying on mythology. The SCHOOL of these philosophers was known as the Ionian SCHOOL, which is a six-letter word that can be used to solve the crossword puzzle.