Webster's Revised Unabridged Dictionary (1913 + 1828)
result(s) from the 1913
Sub"tle (?), a. [Compar. Subtler (?); superl. Subtlest (?).] [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."
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.
4. Smooth and deceptive. [Obs.]
Like to a bowl upon a subtle ground [bowling ground].
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.