Used when someone physically hangs onto something very tightly so they won't fall or be thrown off. She hung on to the boat's railing like grim death during the storm.
Pro Tip 2/3
Fearful Connotation
Implies extreme fear or anxiety while holding on, often during a dangerous situation. During the earthquake, he held on for grim death to the doorframe.
Pro Tip 3/3
Not Casual
More appropriate for serious or dramatic contexts, not casually used in everyday conversation. On the highest cliff, the hiker clung on like grim death to the rope.