aback
adverb
Backwards; back.
phrasal verb
to be taken aback
To be or become very surprised or deeply shocked.
Examples:
From all happenings, Bruno was taken aback mainly by Doctor Barton's subsequent reaction: He stopped the comers with a firm gesture and did not allow them to run to the collapsed hostess's easement. Ohhh, were they documentarily dealing with a weirdish, deep-down malicious man after all? (Context: Grandma Estela seems to be having a fit on the floor in her kitchen. Dr∙ Barton stops everyone, and they are not allowed to help her. What's going on?? Source: J∙ Okram - The Mystery of the Rammed Key.)