1An instance of starting ahead of or before others, as in a race, chase, etc., sometimes by a specified amount; the fact of having such an advantage.
2In extended use: an early or initial advantage, especially over others having the same aim.
3Chiefly with capital initials. A federal educational and welfare programme in the United States, intended to help children in low-income households prepare for schooling.
Mid 19th century; earliest use found in Dundee Courier. From head + start.