Subtle

недоловим

nedolovim

(of an action or movement: very delicate or slight, and thus barely noticeable — see also inconspicuous, unintrusive)

незабележим

nezabeležim

(of an action or movement: very delicate or slight, and thus barely noticeable — see also inconspicuous, unintrusive)

неосезаем

neosezaem

(of an action or movement: very delicate or slight, and thus barely noticeable — see also inconspicuous, unintrusive)

неуловим

neulovim

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

тънък

tǎnǎk

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