• 丹念たんねん — painstaking; careful; thorough
• 丹精たんせい — wholehearted effort; devoted care
• 丹誠たんせい — sincere devotion; true-hearted effort
• 丹砂たんさ — cinnabar; red mineral pigment
• 丹頂たんちょう — red-crowned crane (with a red “丹” spot on its head)
• 牡丹ぼたん — peony

丹 originally pictured a mound or lump of deep red pigment such as 丹砂たんさ. From this concentrated red color, the kanji took on meanings like “vivid red,” and by extension, a heart that is pure, focused, and sincere — putting one’s whole effort into something.