The term 'longtime' can be described by two crossword solutions: VETERAN (7 letters) and OLD (3 letters). A VETERAN is someone who has served in the military for a long period of time, usually at least four years. An OLD person is someone who has lived for a long period of time, usually considered to be over 65 years of age. Both terms imply a long period of time, which is why they are both solutions to the same crossword clue.