expression
immediately; instantly; without a moment's delay
Emphasizes that an action follows another with virtually no gap in time. Often used in narrative or formal contexts. The reading かんぱついれず is an irregular but common variant.
See also: 間髪を入れず
彼は質問に間髪入れず答えた。
He answered the question without a moment's delay.
間髪入れずに次の打者がバッターボックスに入った。
The next batter stepped into the batter's box immediately.
From the expression 間髪を入れず (kanhatsu o irezu), literally 'without putting a hair's breadth in between'. The kanji 間 (interval) and 髪 (hair) combine to suggest an extremely small gap.