| dǔ | serious (illness)/sincere/true |
| 笃 | serious (illness) sincere TRUE |
| 笃专 | with undivided attention |
| 笃信 | to believe firmly devout in one's faith |
| 笃信好学 | sincere belief and diligent study |
| 笃信宗教的 | religiose |
| 笃厚 | honest and generous magnanimous |
| 笃学 | studious diligent in study |
| 笃守 | to comply faithfully sincerely abiding by |
| 笃定 | certain confident (of some outcome) calm and unhurried |
| 笃实 | loyal sincere sound |
| 笃志 | steadfast with single-minded devotion |
| 笃挚 | sincere (in friendship) cordial |
| 笃深 | Deep. |
| 笃爱 | to love deeply devoted to sb |
| 笃病 | seriously ill critical |
| 笃行 | to carry out (obligation) conscientiously to behave sincerely |
| 笃诚 | Very creditable. |