1A men's business suit — a matching jacket and trousers worn for work or formal occasions. A somewhat dated word; younger speakers usually say スーツ, but 背広 is still common among older speakers and in writing. 背広 is ateji.
父はいつも紺の背広を着て出勤する。
My father always wears a navy suit to work.
結婚式に着ていく背広をクリーニングに出した。
I took the suit I'm wearing to the wedding to the cleaners.
最近の若い人は「背広」より「スーツ」と言うことが多い。
These days young people more often say スーツ rather than 背広.
古い写真には背広姿の祖父が写っていた。
In the old photo, my grandfather was shown wearing a suit.