The Collaborative International Dictionary of English v.0.48:

Premier \Pre"mi*er\, a. [F. premier, fr. L. primarius of the
   first rank, principal, fr. primus the first. See Primary,
   Prime, a.]
   1. First; chief; principal; as, the premier place; premier
      minister. --Camden. Swift.
      [1913 Webster]

   2. Most ancient; -- said of the peer bearing the oldest title
      of his degree.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Premier \Pre"mi*er\, n.
   The first minister of state; the prime minister.
   [1913 Webster]

WordNet (r) 3.0 (2006):

premier
    adj 1: first in rank or degree; "an architect of premier rank";
           "the prime minister" [syn: premier(a), prime(a)]
    2: preceding all others in time; "the premiere showing" [syn:
       premier, premiere]
    n 1: the person who holds the position of head of the government
         in the United Kingdom [syn: Prime Minister, PM,
         premier]
    2: the person who is head of state (in several countries) [syn:
       chancellor, premier, prime minister]
    v 1: be performed for the first time; "We premiered the opera of
         the young composer and it was a critical success" [syn:
         premier, premiere]
    2: perform a work for the first time [syn: premier,
       premiere]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "premier":
   PM, all-absorbing, arch, capital, cardinal, champion, chancellor,
   chief, chief executive, chief of state, controlling, dewan, doge,
   dominant, first, foremost, front, grand vizier, head,
   head of state, highest, highest-ranking, leading, maiden, main,
   master, overriding, overruling, paramount, predominant, preeminent,
   president, primary, prime, prime minister, principal, ranking,
   supreme, top, top-ranking, topmost, uppermost