Hair- or whip-like cylindrical structure arising from the cell surface and covered with the common cell membrane. Flagella are usually characterized on the basis of their number, position and arrangements on the body, and are sometimes covered by hairs or scales.

Flagella are used mainly for locomotion, the creation of water currents for food capture and other movements within an organism.

Alternative forms for Flagellum : Flagellate, Flagellated.