Function: intransitive verb
Date: 15th century
1 : QUARREL also : to cut off relations over a quarrel <former friends who have fallen out >
2 : TURN OUT , HAPPEN <expected to be in the States ⋯ , but things fell out otherwise ― Mark Twain>
3 a : to leave one's place in the ranks b : to leave a building in order to take one's place in a military formation