Definition of subtlest:
(adj) :
Senses relating to tangible things.
(adj) :
Of an action or movement: very delicate or slight, and thus barely noticeable; not obvious; inconspicuous, unintrusive.
(adj) :
Senses relating to intangible things.
(adj) :
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.
(adj) :
Giving only a slight impression; elusive, indistinct; also, skilfully restrained or understated.
(adj) :
Of an artist, a musician, etc.: having a light touch; sensitive.