The Collaborative International Dictionary of English v.0.48:
Subtile \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.
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
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.
The subtile influence of an intellect like
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.
[1913 Webster] -- Sub"tile*ly, adv. --
Moby Thesaurus II by Grady Ward, 1.0:
96 Moby Thesaurus words for "subtile":
Byzantine, Machiavellian, Machiavellic, acute, adulterated,
air-built, airy, arch, artful, astute, attenuate, attenuated,
cagey, calculating, canny, chimerical, clever, cloud-built, crafty,
cunning, cut, cute, dainty, deceitful, deep, deep-laid, delicate,
designing, devious, dilute, diluted, diplomatic, dreamlike,
ethereal, fanciful, fatuitous, fatuous, feline, fine, flimsy, foxy,
gaseous, gossamery, guileful, illusory, imaginary, ingenious,
insidious, insubstantial, inventive, knowing, pawky, phantomlike,
politic, rare, rarefied, ready, resourceful, scheming, serpentine,
shadowy, sharp, shifty, shrewd, slick, slight, slippery, sly,
smooth, snaky, sneaky, sophistical, spirituous, stealthy,
strategic, subtle, supple, tactical, tenuous, thin, thinned,
thinned-out, trickish, tricksy, tricky, uncompact, uncompressed,
unreal, unsubstantial, vaporous, vulpine, wary, watered,
watered-down, wily, windy