superl smooth and deceptive.
2. subtle ·superl cunningly devised; crafty; treacherous; as, a subtle stratagem.
3. subtle ·superl sly in design; artful; cunning; insinuating; subtile;
applied to persons; as, a subtle foe.
4. subtle ·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.