veto UK /ˈviːtəʊ/US /ˈvi.toʊ/noun 4verb 2forms 4 noun4 •A political right to disapprove of (and thereby stop) the process of a decision, a law etc. •An invocation of that right.Now, Republican legislators cannot afford to lose a single seat, in either chamber, if they want to continue to override his vetoes. — 2024 •An authoritative prohibition or negative; a forbidding; an interdiction.This contemptuous veto of her husband's on any intimacy with her family. — 1876 •A technique or mechanism for discarding what would otherwise constitute a false positive in a scientific experiment.An outer detector (OD) region will act as both a passive shield for low energy backgrounds and an active veto for cosmic ray muons. — 2021 verb2 •To use a veto against.The president vetoed the bill. •To countermand.Mom and Dad vetoed our menu preferences for the holiday meal. formsvetoed · vetoing · vetoes · vetos