Subtle

1. Hard to grasp; not obvious or easily understood; barely noticeable. Antonym: simple
2. (of a thing) Cleverly contrived.
3. (of a person or animal) Cunning, skillful.Synonyms: crafty, cunning, skillful
4. Insidious. Synonyms: deceptive, malicious
5. Tenuous; rarefied; of low density or thin consistency.
6. (obsolete) Refined; exquisite.