The term 'Sign of Fall' refers to the three astrological signs that fall within the season of autumn, which are LIBRA (5 letters), SAGITTARIUS (11 letters), and Scorpio (7 letters). LIBRA is the seventh sign of the zodiac and is symbolized by the scales, representing balance and justice. SAGITTARIUS is the ninth sign of the zodiac and is symbolized by an archer, representing ambition and exploration. Scorpio is the eighth sign of the zodiac and is symbolized by a scorpion, representing intensity and passion. All three of these signs are associated with the season of fall, making them the 'Signs of Fall'.