adj acute; piercing; searching.
2. subtile ·adj characterized by nicety of discrimination; discerning; delicate; refined; subtle.
3. subtile ·adj thin; not dense or gross; rare; as, subtile air; subtile vapor; a subtile medium.
4. subtile ·adj delicately constituted or constructed; nice; fine; delicate; tenuous; finely woven.
5. subtile ·adj sly; artful; cunning; crafty; subtle; as, a subtile person; a subtile adversary; a subtile scheme.