From Middle English dirti, alteration of earlier dritti, equivalent to dirt + -y. Cognate with Middle Low German drēterich (“dirty”). See also drite. dirty (comparative dirtier, superlative dirtiest) Despite a walk in the rain, my shoes weren't too dirty. dirty, filthy, foul, nasty, squalid mean conspicuously unclean or impure. dirty emphasizes the presence of dirt more than an emotional reaction to it. filthy carries a strong suggestion of offensiveness and typically of gradually accumulated dirt that begrimes and besmears. DIRTY - Synonyms, related words and examples | Cambridge English Thesaurus " don't dirty your clothes when you play outside!"; Derived forms: dirtier, dirtied, dirtying, dirtiest, dirties.