The Collaborative International Dictionary of English v.0.48:

Flagstaff \Flag"staff`\, n.; pl. -stavesor -staffs.
   A staff[4] on which a flag is hoisted.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Flagstaff
    n 1: a town in north central Arizona; site of an important
         observatory
    2: a tall staff or pole on which a flag is raised [syn:
       flagpole, flagstaff]

U.S. Gazetteer Places (2000):

Flagstaff, AZ -- U.S. city in Arizona
   Population (2000):    52894
   Housing Units (2000): 21396
   Land area (2000):     63.579496 sq. miles (164.670132 sq. km)
   Water area (2000):    0.036838 sq. miles (0.095411 sq. km)
   Total area (2000):    63.616334 sq. miles (164.765543 sq. km)
   FIPS code:            23620
   Located within:       Arizona (AZ), FIPS 04
   Location:             35.199160 N, 111.630991 W
   ZIP Codes (1990):     86001 86004
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Flagstaff, AZ
    Flagstaff