astonishing vs astounding

astonishing and astounding both are adjectives.

Word	Noun	Adjective	Verb	Adverb
astonishing	No	Yes	No	No
astounding	No	Yes	No	No

As adjectives, astonishing and astounding are synonyms defined as:

astonishing and astounding: so surprisingly impressive as to stun or overwhelm

Other synonyms of astonishing include staggering, stupefying.

astonishing (adjective)	astounding (adjective)
so surprisingly impressive as to stun or overwhelm	so surprisingly impressive as to stun or overwhelm
surprising greatly	bewildering or striking dumb with wonder