1) Abstract 2) French word used in English 3) Intangible 4) Not palpable 5) Not perceptible to the touch 1) Abstract 2) Imperceptible 3) Indescribable 4) Intangible 5) Subtle 6) Unperceivable 
• (a.) Not apprehensible, or readily apprehensible, by the mind; unreal; as, impalpable distinctions. • (a.) Not material; intangible; incorporeal. • (a.) Not palpable; that cannot be felt; extremely fine, so that no grit can be perceived by touch.
(im-pal´pә-bәl) not detectable by touch.
Im·pal'pa·ble adjective [ Prefix im- not + palpable : confer French impalpable .] 1. Not palpable; that cannot be felt; extremely fine, so that no grit can be perceived by touch. ' Impalpable powder.' Boyle. 2. Not material; intangible; incorporeal...
[adj] - not perceptible to the touch 2. [adj] - imperceptible to the senses or the mind
impalpable, impalpably, impalpability 1. Not palpable; incapable of being perceived by the sense of touch; intangible. 2. Difficult for the mind to grasp readily or easily; such as, impalpable distinctions. 3. With reference to a powder, so fine that when rubbed between the fingers no grit is felt. 4. Impossible of being detected by touch; extrem...
adjective not perceptible to the touch; `an impalpable pulse`
not palpable; incapable of being perceived by the sense of touch; intangible. · difficult for the mind to grasp readily or easily: impalpable distinctions. · (of powder) so fine that when rubbed between the fingers no grit is felt.