Annual means happening once every year or lasting for one year. Your birthday is an annual event: it comes around every twelve months. Schools hold annual science fairs, families might take annual summer vacations, and many organizations have annual meetings where members gather to discuss the past year and plan ahead.

When you see annual in front of something, it tells you to expect it yearly. A magazine might publish an annual issue reviewing the year's biggest stories. Your doctor might recommend an annual checkup to make sure you're healthy.

Annual can also describe plants that complete their entire life cycle in one year, like marigolds or zinnias. These annuals sprout from seeds, grow, flower, make new seeds, and die all within a single growing season, unlike perennials that come back year after year.

When something happens twice a year, we call it biannual or semiannual. The prefix bi- means two, while semi- means half. (Be careful: biannual is sometimes used to mean every two years. Biennial means every two years.)