Endanger/ɪnˈdeɪndʒər/ Definition 1 of 2Pro Tip 1/3Physical Harm Use 'endanger' when someone's physical safety is at risk. Distracted driving endangers everyone on the road. Pro Tip 2/3Environment Focus 'Endanger' is often used when discussing the protection of the environment. Polluting rivers with plastics endangers marine life. Pro Tip 3/3Severity Level Use 'endanger' to imply a high level of risk or threat. Leaving the campfire unattended could endanger the entire forest.