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.
      [1913 Webster]

   2. To soil or sully; to tarnish, as reputation; to taint.
      [1913 Webster]

            He is . . . among the greatest prelates of this age,
            however his character may be defiled by . . . dirty
            hands.                                --Swift.
      [1913 Webster]

   3. To injure in purity of character; to corrupt.
      [1913 Webster]

            Defile not yourselves with the idols of Egypt.
                                                  --Ezek. xx. 7.
      [1913 Webster]

   4. To corrupt the chastity of; to debauch; to violate; to
      rape.
      [1913 Webster]

            The husband murder'd and the wife defiled. --Prior.
      [1913 Webster]

   5. To make ceremonially unclean; to pollute.
      [1913 Webster]

            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]

Moby Thesaurus II by Grady Ward, 1.0:

271 Moby Thesaurus words for "defile":
   abuse, abysm, abyss, access, adulterate, afflict, aggrieve, aisle,
   alley, alloy, ambulatory, aperture, arcade, arroyo, artery,
   attaint, avenue, backpack, befoul, benasty, besmear, besmirch,
   bespatter, betray, bewitch, blacken, blight, blot, blow upon,
   bottleneck, box canyon, brand, breach, break, call names, canal,
   canker, canyon, cavity, censure, channel, chap, chasm, cheapen,
   check, chimney, chink, cleft, cleuch, cloister, clough, coarsen,
   col, colonnade, communication, condemn, conduit, confound,
   connection, contaminate, convert, corridor, corrupt, coulee,
   couloir, covered way, crack, cranny, crevasse, crevice, cut, cwm,
   damage, debase, debauch, deceive, defalcate, defame, deflorate,
   deflower, degenerate, degrade, dell, demoralize, denature,
   denigrate, deprave, desecrate, despoil, destroy, devalue, dike,
   dirty, disadvantage, disapprove, discolor, dishonor, disparage,
   disserve, distort, distress, ditch, divert, do a mischief, do evil,
   do ill, do wrong, do wrong by, donga, doom, draw, embezzle,
   engage in personalities, envenom, excavation, exit, expose,
   expose to infamy, fault, ferry, file, file off, fissure, flaw,
   flume, footslog, force, ford, foul, fracture, furrow, gallery, gap,
   gape, gash, get into trouble, gibbet, go on parade, goose-step,
   gorge, groove, gulch, gulf, gully, hang in effigy, harass, harm,
   heap dirt upon, hex, hike, hole, hurt, impair, incision, infect,
   injure, inlet, interchange, intersection, isthmus, jinx, joint,
   junction, kloof, lane, lead astray, leak, maladminister, maltreat,
   march, march past, menace, mess, mess up, misapply, misappropriate,
   misemploy, mishandle, mislead, mismanage, mistreat, misuse, moat,
   molest, muckrake, mush, narrow, narrows, nasty, neck, notch,
   nullah, opening, outlet, outrage, overpass, parade, pass, passage,
   passageway, peculate, persecute, pervert, pilfer, pillory,
   play havoc with, play hob with, poison, pollute, portico,
   prejudice, profane, promenade, prostitute, railroad tunnel, rape,
   ravage, ravine, ravish, rent, reprimand, revile, rift, rime, ruin,
   rupture, savage, scathe, scissure, seam, seduce, shame, slit, slot,
   slur, smear, smirch, soil, split, spoil, stain, stigmatize, strait,
   sully, taint, tar, tarnish, threaten, throat, throw mud at,
   torment, torture, traject, trajet, tramp, trench, tunnel, twist,
   ulcerate, underpass, valley, vilify, violate, vitiate, void,
   vulgarize, wadi, warp, wound, wreak havoc on, wrong