The Collaborative International Dictionary of English v.0.48:

Defile \De*file"\ (d[-e]*f[imac]l"), v. i. [imp. & p. p.
   Defiled (d[-e]*f[imac]ld"); p. pr. & vb. n. Defiling.]
   [F. d['e]filer; pref. d['e]-, for des- (L. dis-) + file a row
   or line. See File a row.]
   To march off in a line, file by file; to file off.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Defile \De*file"\, v. t. (Mil.)
   Same as Defilade.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Defile \De*file"\ (d[-e]*f[imac]l" or d[=e]"f[imac]l; 277), n.
   [Cf. F. d['e]fil['e], fr. d['e]filer to defile.]
   1. Any narrow passage or gorge in which troops can march only
      in a file, or with a narrow front; a long, narrow pass
      between hills, rocks, etc.
      [1913 Webster]

   2. (Mil.) The act of defilading a fortress, or of raising the
      exterior works in order to protect the interior. See
      Defilade.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Defile \De*file"\ (d[-e]*f[imac]l"), v. t. [OE. defoulen,
   -foilen, to tread down, OF. defouler; de- + fouler to trample
   (see Full, v. t.), and OE. defoulen to foul (influenced in
   form by the older verb defoilen). See File to defile,
   Foul, Defoul.]
   1. To make foul or impure; to make filthy; to dirty; to
      befoul; to pollute.
      [1913 Webster]

            They that touch pitch will be defiled. --Shak.
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   2. To soil or sully; to tarnish, as reputation; to taint.
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            He is . . . among the greatest prelates of this age,
            however his character may be defiled by . . . dirty
            hands.                                --Swift.
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   3. To injure in purity of character; to corrupt.
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            Defile not yourselves with the idols of Egypt.
                                                  --Ezek. xx. 7.
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   4. To corrupt the chastity of; to debauch; to violate; to
      rape.
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            The husband murder'd and the wife defiled. --Prior.
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   5. To make ceremonially unclean; to pollute.
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            That which dieth of itself, or is torn with beasts,
            he shall not eat to defile therewith. --Lev. xxii.
                                                  8.
      [1913 Webster]

WordNet (r) 3.0 (2006):

defile
    n 1: a narrow pass (especially one between mountains) [syn:
         defile, gorge]
    v 1: place under suspicion or cast doubt upon; "sully someone's
         reputation" [syn: defile, sully, corrupt, taint,
         cloud]
    2: make dirty or spotty, as by exposure to air; also used
       metaphorically; "The silver was tarnished by the long
       exposure to the air"; "Her reputation was sullied after the
       affair with a married man" [syn: tarnish, stain,
       maculate, sully, defile]
    3: spot, stain, or pollute; "The townspeople defiled the river
       by emptying raw sewage into it" [syn: foul, befoul,
       defile, maculate]