Subtil
SUB'TIL, adjective [Latin subtilis. This word is often written subtle, but less properly.]
1. Thin; not dense or gross; as subtil air; subtil vapor; a subtil medium.
2. Nice; fine; delicate.
I do distinguish plain
Each subtil line of her immortal face.
3. Acute; piercing; as subtil pain.
4. Sly; artful; cunning; crafty; insinuating; as a subtil person; a subtil adversary.
5. Planned by art; deceitful; as a subtil scheme.
6. Deceitful; treacherous.
7. Refined; fine; acute; as a subtil argument.