• 危篤キトク — critical condition; life-threatening illness
• 篤志トクシ — charitable goodwill; generous support
• 篤信トクシン — deep, devout faith
• 篤学トクガク — diligent, serious study

The bamboo radical on top suggests careful support or framework, while the lower part gives the sound and the idea of something weighty. Together, 篤 points to feelings or situations that are deep and serious — from sincere devotion to a critically serious illness.