1. (

• intangible ,
• impalpable ,

) incapable of being perceived by the senses especially the sense of touch; "the intangible constituent of energy"- James Jeans ;

2. (

• impalpable

) imperceptible to the senses or the mind; "an impalpable cloud"; "impalpable shadows"; "impalpable distinctions"; "as impalpable as a dream" ;

3. (

• impalpable

) not perceptible to the touch; "an impalpable pulse" ;