Definitions for "Imperceptible"
Not perceptible; not to be apprehended or cognized by the senses; not discernible by the mind; not easily apprehended.
impossible or difficult to perceive by the mind or senses; "an imperceptible drop in temperature"; "an imperceptible nod"; "color is unperceivable to the touch"
adj. Impossible or difficult to perceive by the mind or senses; hard to sense or realize.