Main Entry: fall out

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