To learn a lewd man this subtility.
Chaucer.
4. Slyness in design; artifice; guile; a cunning design or artifice; a
trick; subtlety.
O full of all subtility and all mischief.
Acts xiii. 10.
In senses 2, 3, and 4 the word is more commonly written subtlety.
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." Shak.