The term 'LOSE VIGOR' can be broken down into four crossword solutions: SAG (3 letters), FADE (4 letters), FAIL (4 letters), and FLAG (4 letters). SAG means to droop or bend, FADE means to gradually become weaker or less intense, FAIL means to not succeed, and FLAG means to become weaker or less vigorous. Together, these words describe the process of losing vigor, which is the gradual weakening of energy, strength, or enthusiasm.