1. (a.) Elusive; sly in design; insinuating; refined; as, a subtle difference\.

2. (superl.) Cunningly devised; crafty; treacherous; as, a subtle stratagem.

3. (superl.) Characterized by refinement and niceness in drawing distinctions; nicely discriminating; -- said of persons; as, a subtle logician; refined; tenuous; sinuous; insinuating; hence, penetrative or pervasive; -- said of the mind; its faculties, or its operations; as, a subtle intellect; a subtle imagination; a subtle process of thought; also, difficult of apprehension; elusive.

4. (superl.) Smooth and deceptive.

Byzantine Machiavellian Machiavellic abstruse accurate acute adulterated air-built airy analytic analytical appreciative arcane arch artful astute attentive attenuate attenuated balled up boyish cagey calculating canny casuistic chimerical civilized clever close cloud-built complex complicated concealed confounded confused conscientious constant convoluted correct crabbed crafty creamy critical cultivated cultured cunning cut cute daedal dainty deceitful deceptive deep deep-laid delicate demanding designing detailed devious dexterous diaphanous differential dilute diluted diplomatic direct discriminate discriminating discriminative distinctive distinguishing dreamlike eggshell elaborate elegant elusive embrangled entangled ethereal even exact exacting exigent express exquisite faint faithful fanciful fastidious fatuitous fatuous feline fine fine-drawn finespun finical finicking finicky flat flimsy fouled up foxy frail fussy gaseous gauzy girlish gloss gossamer gossamery graceful gracile gracious guileful hairline hairsplitting hidden illusory imaginary implicated inerrable inerrant infallible ingenious insidious insubstantial intricate inventive involuted involved iridescent knotted knowing labyrinthian labyrinthine lacy light loused up many-faceted mathematical matted mazy meandering mellow messed up meticulous micrometrically precise microscopic minute misty mixed up mother-of-pearl mucked up multifarious nacreous narrow nebulous nice obscure opalescent pale papery particular pastel patinaed pawky pearly perplexed phantomlike pinpoint polished politic precise precisianistic precisionistic profound punctilious punctual quiet ramified rare rarefied ratiocinative ready recondite refined religious religiously exact remote resourceful rigid rigorous roundabout sad scheming scientific scientifically exact screwed up scrupulous scrutinizing selective semigloss sensitive serpentine severe shadowy sharp shifty shrewd simple skillful slender slenderish slick slight slight-made slim slimmish slimy slinky slippery sly small smarmy smart smooth snaky snarled sneaky sober soft soft-colored soft-hued softened somber sophistical sophisticated spirituous square stealthy strategic strict subdued subtile supple svelte sweet sylphlike tactful tactical tangled tangly tender tenuous