\Sub"til*ty\, n. [Contr. fr. subtility.]
1. The quality or state of being subtile; thinness; fineness;
   as, the subtility of air or light.
2. Refinement; extreme acuteness; subtlety.
         Intelligible discourses are spoiled by too much
         subtility in nice divisions.          --Locke.
3. Cunning; skill; craft. [Obs.]
         To learn a lewd man this subtility.   --Chaucer.
4. Slyness in design; artifice; guile; a cunning design or
   artifice; a trick; subtlety.
         O full of all subtility and all mischief. --Acts
                                               xiii. 10.
Note: In senses 2, 3, and 4 the word is more commonly written
      subtlety.