Subtile1. (a.) Thin; not dense or gross; rare; as, subtle air; subtle vapor; a subtle medium.
2. (a.) Delicately constituted or constructed; nice; fine; delicate; tenuous; finely woven.
3. (a.) Acute; piercing; searching.
4. (a.) Characterized by nicety of discrimination; discerning; delicate; refined; subtle.
5. (a.) Sly; artful; cunning; crafty; subtle; as, a subtle person; a subtle adversary; a subtle scheme.
Thesaurus Entries
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