Dirtier means less clean than before. Dirtier than yesterday, gets dirtier, dirtier still.
It is the comparative of dirty, with the y turning to i as in happier. Of fuel and industry it means producing more pollution — a dirtier power station. Of a joke or a fight it means more indecent or more unfair. Note that dirt comes from a Norse word for excrement.
1adjectivedirtierLess clean than before.
“The kitchen looked even dirtier after the children tried to clean it.”
dirtier is a comparison of cleanliness.
Middle English
dirti
English
dirty
English, today
dirtier
dirty comes from Middle English dirti, alteration of earlier dritti, equivalent to dirt + y. Cognate with Middle Low German drēterich (“dirty”). See also drite.
Etymology from Wiktionary, CC BY-SA