Suddenly; abruptly; all of a sudden — something happening without warning (often expresses surprise or displeasure). Usually written in kana.
いきなり雨が降ってきて、傘を持っていなかった。
It started raining suddenly and I didn't have an umbrella.
彼は会議の途中でいきなり席を立った。
He abruptly stood up in the middle of the meeting.
いきなりそんなことを言われても困る。
I'm at a loss when you say something like that out of the blue.