Um

from The Collaborative International Dictionary of English v.0.48

Om \Om\, interj. & n. [Also {Aum}, {Um}.] [Skr. [=o]m.]
   A mystic syllable or ejaculation used by Hindus and Buddhists
   in religious rites, -- orig. among the Hindus an exclamation
   of assent, like Amen, then an invocation, and later a symbol
   of the trinity formed by Vishnu, Siva, and Brahma.

   {Om mani padme hun}, a sacred formula of buddhism (esp. of
      the Lamaists) translated "O, the Jewel in the Lotus,
      Amen," and referring to Amitabha, who is commonly
      represented as standing or sitting within a lotus.
      [Webster 1913 Suppl.]

from The Free On-line Dictionary of Computing (8 July 2008)

um

   <networking> The {country code} for United States minor
   outlying islands.

   (1999-01-27)