What is a synonym for ashtonish?

"Astonish" doesn't have a true synonym, as it's a fairly unique word. However, depending on the context, you could use words that convey similar meanings:

For a stronger reaction:

* Awe: This implies a sense of wonder and respect.

* Overwhelm: This suggests a feeling of being completely consumed by emotion.

* Stunner: This is a more informal and playful term for something that is incredibly impressive.

For a milder reaction:

* Surprise: This is a more general term for an unexpected event.

* Startle: This implies a sudden and brief feeling of surprise.

* Amaze: This suggests a feeling of wonder and admiration.

For a more specific reaction:

* Dumbfound: This suggests a feeling of being speechless with surprise.

* Befuddle: This implies a feeling of confusion and bewilderment.

* Disconcert: This suggests a feeling of being thrown off balance or unsettled.

The best synonym for "astonish" will depend on the specific situation and the intended meaning.