(1):

(n.) A fall or plunge headforemost, as while riding a bicycle, or in bathing; as, to take a header.

(2):

(n.) A reaper for wheat, that cuts off the heads only.

(3):

(n.) In framing, the piece of timber fitted between two trimmers, and supported by them, and carrying the ends of the tailpieces.

(4):

(n.) A brick or stone laid with its shorter face or head in the surface of the wall.

(5):

(n.) One who, or that which, heads nails, rivets, etc., esp. a machine for heading.

(6):

(n.) One who heads a movement, a party, or a mob; head; chief; leader.