de·file¹ / diˈfīl/ • v. [tr.] sully, mar, or spoil. ∎  desecrate or profane (something sacred). ∎ archaic violate the chastity of (a woman).DERIVATIVES: de·file·ment n.de·fil·er n.de·file² / diˈfīl; ˈdēˌfīl/ • n. a steep-sided, narrow gorge or passage (originally one requiring troops to march in single file).• v. [intr.] archaic (of troops) march in single file: we emerged after defiling through the mountainsides.

defile 1 make foul or unclean. XIV. alt. of †defoul, †defoil, by assoc. with synon. †befile, OE. befȳlan (f. BE- + fȳlan, f. fūl FOUL). The earlier defoul (XIII), of which there is an unexpl. var. defoil (XIV), was — OF. def(o)uler trample down, outrage, violate, f. DE- 1 + fouler tread, trample :- Rom. *fullāre stamp, f. L. fullō FULLER.
Hence defilement XVII.

defile 2 narrow pass between mountains. XVII. orig. defilé, defilee — F. défilé, sb. use of pp. of défiler march by files, f. DE- 2 + file FILE 2. For the loss of the final syll. cf. ASSIGN 2.