defileyoudaoicibaDictYouDict[defile 词源字典]
defile: Defile ‘make dirty’ [14] and defile ‘narrow pass’ [17] are distinct words in English. The former has a rather complex history. It was originally acquired in the 13th century as defoul, borrowed from Old French defouler ‘trample down, injure’; this was a compound verb formed from the prefix de- ‘down’ and fouler ‘tread’, which in turn goes back via Vulgar Latin *fullāre to Latin fullō ‘person who cleans and thickens cloth by stamping on it’, source of English fuller [OE].

In the 14th century defoul started to turn into defile under the influence of the synonymous (and now obsolete) befile [OE], a compound verb derived ultimately from the adjective foul. Defile ‘narrow pass’ was borrowed from French défilé, originally the past participle of défiler, a compound verb based on filer ‘march in a column’ (which is a close relative of English file).

=> fuller; file[defile etymology, defile origin, 英语词源]
defile (v.)youdaoicibaDictYouDict
c. 1400, "to desecrate, profane;" mid-15c., "to make foul or dirty," alteration of earlier defoulen, from Old French defouler "trample down, violate," also "ill-treat, dishonor," from de- "down" (see de-) + foler "to tread," from Latin fullo "person who cleans and thickens cloth by stamping on it" (see foil (v.)).

The alteration (or re-formation) in English is from influence of Middle English filen (v.) "to render foul; make unclean or impure," literal and figurative, from Old English fylen (trans.), related to Old English fulian (intrans.) "to become foul, rot," from the source of foul (adj.). Compare befoul, which also had a parallel form befilen. Related: Defiled; defiling.
defile (n.)youdaoicibaDictYouDict
"narrow passage," 1640s, especially in a military sense, "a narrow passage down which troops can march only in single file," from French défilé, noun use of past participle of défiler "march by files" (17c.), from de- "off" (see de-) + file "row," from Latin filum "thread" (see file (v.1)). The verb in this sense is 1705, from French défiler.