An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed. Some seedless plants can also be considered annuals even though they do not grow a flower.
In gardening, annual often refers to a plant grown outdoors in the spring and summer and surviving just for one growing season. Many food plants are, or are grown as, annuals, including virtually all domesticated grains.