\Sub"tile\, a. [L. subtilis. See {Subtile}.]
1. Thin; not dense or gross; rare; as, subtile air; subtile
   vapor; a subtile medium.
2. Delicately constituted or constructed; nice; fine;
   delicate; tenuous; finely woven. ``A sotil [subtile]
   twine's thread.'' --Chaucer.
         More subtile web Arachne can not spin. --Spenser.
         I do distinguish plain Each subtile line of her
         immortal face.                        --Sir J.
                                               Davies.
3. Acute; piercing; searching.
         The slow disease and subtile pain.    --Prior.
5. Characterized by nicety of discrimination; discerning;
   delicate; refined; subtle. [In this sense now commonly
   written {subtle}.]
         The genius of the Spanish people is exquisitely
         subtile, without being at all acute; hence there is
         so much humor and so little wit in their literature.
         The genius of the Italians, on the contrary, is
         acute, profound, and sensual, but not subtile; hence
         what they think to be humorous, is merely witty.
                                               --Coleridge.
         The subtile influence of an intellect like
         Emerson's.                            --Hawthorne.
5. Sly; artful; cunning; crafty; subtle; as, a subtile
   person; a subtile adversary; a subtile scheme. [In this
   sense now commonly written {subtle}.]
Syn: {Subtile}, {Acute}.
Usage: In acute the image is that of a needle's point; in
       subtile that of a thread spun out to fineness. The
       acute intellect pierces to its aim; the subtile (or
       subtle) intellect winds its way through obstacles. --
       {Sub"tile*ly}, adv. -- {Sub"tile*ness}, n.