Antonyms for the phrase "gave warning" include "kept silent," "ignored," "approved," "encouraged," and "endorsed." When we say someone "gave warning," we mean they alerted others to potential danger, harm, or consequences. However, the antonyms emphasize the exact opposite by downplaying or even encouraging the very thing that the warning sought to prevent. For instance, when a supervisor "kept silent" instead of "gave warning" about a faulty machine, they risked putting their workers in harm's way. Similarly, if a parent "ignored" their child's warning about an incoming storm, they could have endangered their life.