The term 'VERY LONG SPELL' can be broken down into three crossword solutions: AGE (3 letters), EON (3 letters), and EONS (4 letters). An AGE is a period of time, usually measured in years, that is associated with a particular stage in the development of a person or thing. An EON is an indefinite and very long period of time, typically one marked by significant changes or important events. EONS are the longest units of geological time and are divided into eras. EONS are also used to refer to a very long period of time, often in a figurative sense.