adj

• (heraldry) Most ancient; first to hold a specified status.
  "PREMIER, a. This French word, which signifies first, is used by English Heralds to signify the most ancient Peer of any Degree by Creation; as Premier Baron, &c."

noun

• (politics, UK, Westminster system) The head of government in parliament and leader of the cabinet.
  "1871 July 29, “Our Tyrant”, The Spectator, Volume 303, Issues 9308-9315, page 910, Mr. Gladstone had literally no option. Not to coerce the Lords was to coerce the Commons to continue purchase in spite of their repeated votes for its abolition, and this the Premier had as little the power as the will to do."
• (politics, UK, Westminster system) The head of government in parliament and leader of the cabinet.
  "More surprising than the company′s activities and interests were those of the premier of Ontario, Mitchell Hepburn."
• (politics, non-Westminster) The government leader in a legislative congress or leader of a government-level administrative body; the head of government.
  "1983, Guo Zhou, China & the World, Volume 4, Beijing Review, page 13, This shows that our policy of strengthening friendly ties with Africa as developed by Chairman Mao Zedong and Premier Zhou Enlai is a correct one and that it has won popular support in Africa."
• (nautical, slang) The first lieutenant or other second-in-command officer of a ship.