also: もうぜん
taru-adjective, adverb taking the 'to' particle
dumbfounded; in a daze; stunned
Describes a state of being so shocked or surprised that one is momentarily unable to react. Often used with とする or となる.
突然の知らせに、彼は呆然とした。
He was dumbfounded by the sudden news.
呆然と立ち尽
I could only stand there in a daze.