A grain is a small, hard, dry fruit, commonly known as a caryopsis, which may or may not come with an outer hull layer.
The terms “grains” and “cereal” are often used interchangeably to refer to caryopses, the fruits that come from the grass family. In the fields of agronomy and commerce, seeds or fruits from other plant families may also be called grains if they bear a resemblance to caryopses.
