Flabbergast (verb)

1. To astonish or surprise greatly.
2. To shock or amaze.

Origin:

Mid 19th century: from flabbergast, a dialect variant of flabberghast (an alteration of obsolete affright), from flabber "to confuse, perplex" + ghast "frighten".

Examples:

1. He was flabbergasted by the news.
2. The announcement flabbergasted the audience.
3. The revelation flabbergasted him and he couldn't speak.
4. The sudden change in plans flabbergasted everyone.
5. His reaction was one of flabbergastment when he heard the news.