To conduct the policy, actions, and affairs of a state, organization, or people with authority. The newly elected president will govern the country for the next four years.
To control, influence, or regulate a person, action, or course of events. The rules that govern the game are strict and must be followed by all players.
To serve as a determining or guiding principle. The principles of justice and equality govern the legal system.
(Grammar) Of a word: to require that another word or construction be in a particular grammatical case, mood, or form. In Latin, many prepositions govern the ablative case.