A four-character idiom meaning people of all ages and both sexes; men and women, young and old.
コンサートには老若男女が集まり、大変な賑わいだった。
People of all ages and both sexes gathered at the concert; it was very lively.
この公園は老若男女に人気がある。
This park is popular with people of all ages.
イベントは老若男女問わず参加できます。
The event is open to people of all ages and genders.