The term 'INNER:PREF' can be broken down into two parts. The first part, 'INNER', refers to something that is located WITHIN or INSIDE of something else. The second part, 'PREF', stands for prefix, which is a word or group of letters added to the beginning of a word to change its meaning. The two crossword solutions for this term are 'ENDO' and 'ENTO'. ENDO is a prefix derived from the Greek word 'endon', meaning 'WITHIN' or 'INSIDE'. ENTO is also a prefix derived from the Greek word 'entos', meaning 'WITHIN' or 'INSIDE'. Both ENDO and ENTO are used to describe something that is located WITHIN or INSIDE of something else.