1A somewhat formal or old-fashioned word meaning 'you (people)' — used to refer to a group being addressed, often in speeches or writing.
諸君の協力なしにはこの計画は成功しなかっただろう。
This plan wouldn't have succeeded without all of your cooperation.
諸君の意見をぜひ聞かせてほしい。
I'd really like to hear what all of you think.
先生は諸君に向かって静かにそう言った。
The teacher said that quietly to the assembled students.
2An interjection used to address an audience or readers — more formal and ceremonial than 'minasan', often used by a leader or superior addressing a group of subordinates or students.
諸君！今こそ立ち上がる時だ！
Everyone! Now is the time to rise up!
諸君、これが我々の最後のチャンスだ。
Ladies and gentlemen, this is our last chance.
校長は『諸君』と呼びかけて式辞を始めた。
The principal began the ceremony address by calling out 'shokun'.