| 1. | thin, tenuous, or rarefied, as a fluid or an odor. |
| 2. | fine or delicate in meaning or intent; difficult to perceive or understand: subtle irony. |
| 3. | delicate or faint and mysterious: a subtle smile. |
| 4. | requiring mental acuteness, penetration, or discernment: a subtle philosophy. |
| 5. | characterized by mental acuteness or penetration: a subtle understanding. |
| 6. | cunning, wily, or crafty: a subtle liar. |
| 7. | insidious in operation: subtle poison. |
| 8. | skillful, clever, or ingenious: a subtle painter. |