Subtle

Part of speech: adjective (a.)

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.

Synonyms: Artful; crafty; cunning; shrewd; sly; wily. Subtle is the most comprehensive of these epithets and implies the finest intellectual quality. See Shrewd, and Cunning.