Fennel seed, the seed of the fennel plant, are used as a spice across the Mediterranean, Middle East, and India. They give a sweet, slightly licorice-like flavor to dishes.
Fennel seeds are technically the dried fruit of the fennel plant. The part commonly referred to as "fennel seed" is actually the dried schizocarp, a type of fruit that splits into single-seeded parts when mature. Each part of the schizocarp contains a single seed.