French word douteux comes from French -eux (-ous, -y.), French doute (Doubt.)

Detailed word origin of douteux

Dictionary entry	Language	Definition
-eux	French (fra)	-ous, -y.
doute	French (fra)	Doubt.
douteux	French (fra)	Doubtful, uncertain, questionable (issue, outcome, date etc.). Dubious, questionable (morals, qualities etc.).

Words with the same origin as douteux