プログレッシブ和英中辞典(第4版)の解説
かいこう【開口】
〔開いた入り口〕an opening
通風孔の開口部
a ventilation opening
このビルは開口部が多い
This building has a lot of windows and doors.
開口一番
彼は開口一番恩師を称えた
He began his speech by paying tribute to his teacher.
彼女が開口一番言ったことはそれが相手方の手落ちだということだった
The first thing she said was that it was her opponent's fault.