impalpable -
imperceptible to the senses or the mind; "an impalpable cloud"; "impalpable shadows"; "impalpable distinctions"; "as impalpable as a dream"
palpable,
tangible capable of being perceived; especially capable of being handled or touched or felt; "a barely palpable dust"; "felt sudden anger in a palpable wave"; "the air was warm and close--palpable as cotton"; "a palpable lie"
imperceptible,
unperceivable impossible or difficult to perceive by the mind or senses; "an imperceptible drop in temperature"; "an imperceptible nod"; "color is unperceivable to the touch"
impalpable -
not perceptible to the touch; "an impalpable pulse"
impalpable -
incapable of being perceived by the senses especially the sense of touch; "the intangible constituent of energy"- James Jeans
