WordNet sense 1 (the person who holds the position of head of the government in England):

pm, Prime Minister

WordNet sense 2 (the person who is head of state (in several countries)):

chancellor

WordNet sense 3 (be performed for the first time):

premiere

WordNet sense 4 (first in rank or degree):

prime

WordNet sense 5 (preceding all others in time or space or degree):

first