verblüfft
astonished
Being very surprised, amazed, or speechless, often because something unexpected has happened.
Ich war völlig verblüfft, als sie plötzlich vor der Tür stand.
I was completely astonished when she suddenly appeared at the door.

astonished
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astonished
Being very surprised, amazed, or speechless, often because something unexpected has happened.
Ich war völlig verblüfft, als sie plötzlich vor der Tür stand.
I was completely astonished when she suddenly appeared at the door.

'Verblüfft' (astonished) is the past participle of the verb 'verblüffen' (to astonish) and is usually used like an adjective. The prefix 'ver-' often indicates a change of state here: you move from a state of not knowing to a state of amazement.
Sein Trick hat das Publikum völlig verblüfft.
His trick completely astonished the audience.
You can express the reason for the amazement with 'über' (+ accusative) or with a subordinate clause using 'dass' (that) or 'als' (when).
Die Wissenschaftler waren verblüfft über die Ergebnisse des Experiments.
The scientists were astonished by the results of the experiment.
To emphasize strong amazement, 'verblüfft' (astonished) is often combined with adverbs such as 'völlig' (completely), 'total' (totally), or 'sichtlich' (visibly). It can also be used as an adverb itself.
Er sah mich verblüfft an, als ich ihm die Neuigkeit erzählte.
He looked at me in astonishment when I told him the news.
speechless
'sprachlos' and 'verblüfft' both have to do with strong surprise. 'sprachlos' mainly means that someone briefly cannot say anything because of surprise, shock, or anger. 'verblüfft' means that someone is very surprised or astonished; that person may still be able to speak, though. The words are easy to confuse because astonishment can be so strong that you also become sprachlos. If the reaction 'I can't say anything' is important, use 'sprachlos'. If only the strong amazement is important, 'verblüfft' sounds more natural.

Johanna war verblüfft, weil das alte Gerät wieder funktionierte.
Johanna was astonished because the old device was working again.
Als ihr Chef sie plötzlich lobte, war sie völlig sprachlos.
When her boss suddenly praised her, she was completely speechless.