fountain of youth

fountain of youth noun
plural fountains of youth
fountain of youth
noun
plural fountains of youth
Britannica Dictionary definition of FOUNTAIN OF YOUTH
[count]
1 
in stories and legends or Fountain of Youth : a fountain with magic water
◊ According to legend, anyone who drinks water from the Fountain of Youth will live forever.
2 
: a source of the kind of energy or health that young people usually have