A silo is a cylindrical tower used for bulk storage, like grain silos that stand tall near farms. Another kind of silo is harder to see — military silos are underground.
Farming and war are pretty different, but they both involve silos. You may have seen a silo if you've ever visited a farm. A silo is a tall tower with a cylindrical (rounded) shape. The silo holds anything the farmer needs to store in bulk, especially feed for the animals. Other, non-farm silos hold material such as cement or coal. The military type of silo holds something more dangerous: missiles. These silos store the missiles underground until they’re fired.