subtle

Of an action or movement: very delicate or slight, and thus barely noticeable; not obvious; inconspicuous, unintrusive.

Having a delicate or fine substance or texture; hence, exquisite, refined.

Slender, thin.

Of a substance: finely powdered; also, of particles of a substance: very fine or small.

Of weight: after the tare (“weight of an empty container”) has been subtracted; net.

Of a substance, especially a gas or liquid: of low density or thin consistency; rarefied, tenuous; hence, tending to spread everywhere due to this quality.

Synonym of subtile (“of a ship: narrow, slender”).

Of an argument or concept, words, etc.: requiring one to distinguish between fine points, especially if it is difficult to do so; nice; also (generally), difficult to grasp; not easily understood or obvious.

Giving only a slight impression; elusive, indistinct; also, skilfully restrained or understated.

Of an artist, a musician, etc.: having a light touch; sensitive.