The Collaborative International Dictionary of English v.0.48:

Shelter \Shel"ter\, n. [Cf. OE. scheltrun, shiltroun,
   schelltrome, scheldtrome, a guard, squadron, AS. scildtruma a
   troop of men with shields; scild shield + truma a band of
   men. See Shield, n.]
   1. That which covers or defends from injury or annoyance; a
      protection; a screen.
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            The sick and weak the healing plant shall aid,
            From storms a shelter, and from heat a shade.
                                                  --Pope.
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   2. One who protects; a guardian; a defender.
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            Thou [God] hast been a shelter for me. --Ps. lxi. 3.
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   3. The state of being covered and protected; protection;
      security.
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            Who into shelter takes their tender bloom. --Young.
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   Shelter tent,a small tent made of pieces of cotton duck
      arranged to button together. In field service the soldiers
      carry the pieces.
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   Syn: Asylum; refuge; retreat; covert; sanctuary; protection;
        defense; security.
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WordNet (r) 3.0 (2006):

shelter tent
    n 1: a wedge-shaped tent; usually without a floor or windows
         [syn: pup tent, shelter tent]