- (literally) The main, central lode of a natural resource, near which smaller deposits of the same ore etc. exist.
- Once the Western mining company has exploited a motherlode with state of the art equipment, it often abandons the minor lodes to primitive local enterprise
- (figuratively) The main prize, best cut or pick etc. by far, dwarfing all others.
- Luckily the philistine castle-burglars missed the motherlode: his lordship's historical memorabilia collection