insubstantially vs impalpably

insubstantially and impalpably both are adverbs.

Word	Noun	Adjective	Verb	Adverb
insubstantially	No	No	No	Yes
impalpably	No	No	No	Yes

As adverbs, insubstantially and impalpably are synonyms defined as:

insubstantially and impalpably: not substantially; lacking substantial expression or fullness

insubstantially (adverb)	impalpably (adverb)
not substantially; lacking substantial expression or fullness	not substantially; lacking substantial expression or fullness