a. [ Pref. im- not + palpable: cf. F. impalpable. ] 1. Not palpable; that cannot be felt; extremely fine, so that no grit can be perceived by touch. “Impalpable powder.” Boyle. [ 1913 Webster ]
2. Not material; intangible; incorporeal. “Impalpable, void, and bodiless.” Holland. [ 1913 Webster ]
3. Not apprehensible, or readily apprehensible, by the mind; unreal; as, impalpable distinctions. [ 1913 Webster ]