SUBTLE
insidious, pernicious, subtle
(adjective) working or spreading in a hidden and usually injurious way; “glaucoma is an insidious disease”; “a subtle poison”
elusive, subtle
(adjective) difficult to detect or grasp by the mind or analyze; “his whole attitude had undergone a subtle change”; “a subtle difference”; “that elusive thing the soul”
subtle
(adjective) able to make fine distinctions; “a subtle mind”
Source: WordNet® 3.1
Etymology
Adjective
subtle (comparative subtler or more subtle, superlative subtlest or most subtle)
Hard to grasp; not obvious or easily understood; barely noticeable.
Antonym: simple
(of a thing) Cleverly contrived.
(of a person or animal) Cunning, skillful.
Synonyms: crafty, cunning, skillful
Insidious.
Synonyms: deceptive, malicious
Tenuous; rarefied; of low density or thin consistency.
(obsolete) Refined; exquisite.
Anagrams
• bluest, bluets, bustle, butles, sublet
Source: Wiktionary
Sub"tle, a. [Compar. Subtler; superl. Subtlest.] Etym: [OE. sotil,
subtil, OF. soutil, later subtil, F. subtil, L. subtilis; probably,
originally, woven fine, and fr. sub under + tela a web, fr. texere to
weave. See Text, and cf. Subtile.]
1. Sly in design; artful; cunning; insinuating; subtile; -- applied
to persons; as, a subtle foe. "A subtle traitor." Shak.
2. Cunningly devised; crafty; treacherous; as, a subtle stratagem.
3. 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.
Things remote from use, obscure and subtle. Milton.
4. Smooth and deceptive. [Obs.]
Like to a bowl upon a subtle ground [bowling ground]. Shak.
Syn.
– Artful; crafty; cunning; shrewd; sly; wily. Subtle is the most
comprehensive of these epithets and implies the finest intellectual
quality. See Shrewd, and Cunning.
Source: Webster’s Unabridged Dictionary 1913 Edition