Synonyms of foul-mouthed

1 Syllable
vile, lewd, blue, gross, fast
2 Syllables
loose, hard-core, unclean, coarse, smutty, racy, wanton, taboo, coarser, ribald, bawdy, risqué, lustful, filthy, lewdest, wicked, raunchier, raunchy, coarsest, incult, naughty, rakish
3 Syllables
improper, immoral, immodest, impure, lascivious, x-rated, off-color, erotic, unvirtuous, salacious, unchaste, obscene, scurrilous, licentious, vulgarian, scandalous, lecherous, shameless
4 Syllables
questionable, pornographic, incontinent, suggestive, philistine, profligate, libidinous, libertine
5 Syllables
indelicate, unconventional