Sub·tile a.
 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.”
    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.
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