1. showing sustained enthusiastic action with unflagging vitality; tireless
Usage: formal

Examples

• The indefatigable researcher worked through the night to complete her study.
• His indefatigable efforts to help the homeless earned him community recognition.
• She was an indefatigable advocate for children’s rights.
• The indefatigable athlete trained every day for the Olympics.
• Despite setbacks, the team showed indefatigable determination.
• Her indefatigable spirit inspired everyone around her.