Dumbfound (verb)

1. To surprise and shock someone so much that they are temporarily unable to speak or react.
2. To confound or perplex someone.

Origin:

Late 18th century: from dumb "silent" + found "strike".

Examples:

1. The news dumbfounded her, leaving her at a loss for words.
2. The sudden turn of events dumbfounded the audience.
3. The complexity of the problem dumbfounded the scientists.
4. The proposal dumbfounded the board of directors.
5. The argument dumbfounded his opponent and left him speechless.