1. in a way that is extremely tiring, exhausting, or demanding; with grueling intensity or difficulty
Usage: formed from the adjective 'grueling' (also spelled 'gruelling' in British English)

Examples

• The marathon was gruelingly difficult, testing every runner's endurance.
• She worked gruelingly long hours to meet the project deadline.
• The training regimen was gruelingly intense, pushing athletes to their limits.
• He spent gruelingly long days in the field conducting research.
• The climb up the mountain was gruelingly slow and exhausting.
• The team practiced gruelingly hard throughout the season.