Pronunciation: (sut'l),[key] —adj.,-tler, -tlest. 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.