Etymology
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filth (n.)
Old English fylð "uncleanness, impurity, foulness," from Proto-Germanic *fulitho (source also of Old Saxon fulitha "foulness, filth," Dutch vuilte, Old High German fulida), noun derivative of *fulo- "foul" (see foul (adj.)). A classic case of i-mutation.
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filthy (adj.)

late 12c., fulthe, "corrupt, sinful," from filth + -y (2). Meaning "physically unclean, dirty, noisome" is from late 14c. Meaning "morally dirty, obscene" is from 1530s.

In early use often hardly more emphatic than the mod. dirty; it is now a violent expression of disgust, seldom employed in polite colloquial speech. [OED]

Related: Filthily; filthiness.

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ordure (n.)

late 14c., "dung, excrement, feces; filth, dirt," from Old French ordure "filth, uncleanliness" (12c.), from ord, ort "filthy, dirty, foul," from Latin horridus "dreadful" (see horrid). Related: Ordurous.

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gleet (n.)
mid-14c., "slime, greasy filth," from Old French glete "clay, loam; slime, mud, filth" (12c., Modern French glette), from Latin glitem (nominative glis) "sticky, glutinous ground," back-formation from glittus "sticky."
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gore (n.1)
"thick, clotted blood," Old English gor "dirt, dung, filth, shit," a Germanic word (cognates: Middle Dutch goor "filth, mud;" Old Norse gor "cud;" Old High German gor "animal dung"), of uncertain origin. Sense of "clotted blood" (especially shed in battle) developed by 1560s (gore-blood is from 1550s).
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befoul (v.)
"make foul, cover with filth," from Old English befylan; see be- + foul (v.). Related: Befouled; befouling.
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cleanness (n.)
Old English clænnes "(moral) cleanness, purity, chastity;" see clean (adj.) + -ness. Meaning "absence of dirt or filth" is late 14c.
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cleanliness (n.)

"state of being free from dirth or filth; habit of keeping clean," early 15c., from cleanly + -ness.

Cleanliness is indeed next to godliness. [John Wesley, Sermon "On Dress," c. 1791]
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