Discussions of terrorism assume actual or threatened violence, but the term is regularly used to delegitimize rivals' nonviolent actions. Yet do ordinary citizens accept descriptions of nonviolence as terrorism? Using a preregistered survey-experiment in Israel, a salient conflictual context with diverse repertoires of contention, we find that audiences rate adversary nonviolence close to terrorism, consider it illegitimate, and justify its forceful repression. These perceptions vary by the action's threatened harm, its salience, and respondents' ideology. Explicitly labeling nonviolence as terrorism, moreover, particularly sways middle-of-the-road centrists. These relationships replicate in a lower-salience conflict, albeit with milder absolute judgments, indicating generalizability. Hence, popular perceptions of terrorism are more fluid and manipulable than assumed, potentially undermining the positive effects associated with nonviolent campaigns.