The Collaborative International Dictionary of English v.0.48:

Fiord \Fiord\ (fy?rd; i or y consonant, [sect] 272), n. [Dan. &
   Norw. fiord. See Frith.]
   A narrow inlet of the sea, penetrating between high banks or
   rocks, as on the coasts of Norway and Alaska. [Written also
   fjord.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

fiord
    n 1: a long narrow inlet of the sea between steep cliffs; common
         in Norway [syn: fjord, fiord]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "fiord":
   arm, armlet, bay, bayou, belt, bight, boca, cove, creek, estuary,
   euripus, fjord, frith, gulf, gut, harbor, inlet, kyle, loch, mouth,
   narrow, narrow seas, narrows, natural harbor, reach, road, roads,
   roadstead, sound, strait, straits