v.1. To drop from something: I accidentally knocked my toolbox over and all of my nails fell out.
2. To come out of place. Used of teeth: When I was 12, my last baby tooth fell out. If you don't get your cavity filled, your tooth will fall out!
3. To occur as a natural consequence; turn out: These results fall out directly from the experimental evidence.
4. To come or be revealed to be known, especially by chance: Over the course of their conversation, it fell out that they had all once lived in Chicago.
5. To break a relationship or form a negative relationship as a result of a dispute: The siblings fell out over the inheritance. The law firm was disbanded after the partners fell out.
6. fall out with To break a relationship or form a negative relationship with someone: After John fell out with Alice, they sold their house.