核

1. Origins, structure, and basic meaning

• Structure: 核 (かく) is a single-character noun for a physical nucleus or a figurative core.
• Basic usage: It identifies the center of an atom and the essential role of trust in teamwork.

2. Common pitfalls and similar expressions

• Scientific nucleus and figurative center
  • 原子の核 is material, while a phrase about cooperation uses 核 for the most central sustaining element.