What does H stand for?

What does H mean?

H	How Miscellaneous » Unclassified
H	History Academic & Science » Universities
H	Head Medical » Physiology
H	Head Governmental » NASA
H	Half Miscellaneous » Unit Measures
H	Heart Medical » Physiology
H	Henry Miscellaneous » Unit Measures
H	Hour Miscellaneous » Unit Measures
H	Hands Medical » Physiology
H	Hybrid Academic & Science » Electronics
H	Honor Governmental » Military
H	Hydrogen Academic & Science » Chemistry
H	Hearing Medical » Physiology
H	High Academic & Science » Meteorology
H	Help Miscellaneous » Unclassified
H	Horse Miscellaneous » Farming
H	Height Miscellaneous » Unit Measures
H	Holy Community » Religion
H	Humanities Academic & Science » Universities
H	Helpful Community » Law
H	Her Miscellaneous » Unclassified
H	Hot Academic & Science » Physics
H	Hero Governmental » Military
H	Heaven Community » Religion
H	Harvard Academic & Science » Universities