Cases of word usage

1) an ending that can be seen or could have been seen from the start (foregone)

2) the ability to understand why something happened or how it could have been prevented after the event has occurred (hindsight)

3) (the belief in) the principle that war should and could be abolished (pacifism)

4) not necessary; that could have been avoided (unnecessary)

5) that could not have been imagined (unthought)