H
Hectare	Standard unit for measuring large areas. Equal to 100 by 100 meters.
Hectometer	A hundred meters.
Height	Measurement from top to bottom.
Hemisphere	Half of a sphere.
Hepta-	Prefix meaning seven.
Heptagon	Polygon with seven sides.
Hexa-	Prefix meaning six.
Hexagon	Polygon with six sides.
Hexahedron	Polyhedron with six faces.
Highest Common Factor	Largest number that would divide two or more numbers exactly.
Horizontal	Parallel to the horizon.
Hypotenuse	Longest side in a right triangle.