A cadre is a small group of people who have been specially trained, and who form the tight centre of a larger body — a political party, an army, or a profession. The idea is that this little team knows the work well and can lead, teach, or hold things together.

A cadre cadre（骨幹） is是指 a small group of people一小群人 who have been specially trained他們受過特別訓練 and who form the tight centre並且形成核心 of a larger body在一個更大團體裡 a political party像是政黨 an army軍隊 or a profession或某個專業領域 The idea is重點在於 that this little team這個小團隊 knows the work well很懂這份工作 and can lead能夠帶領 teach教導 or hold things together或把事情凝聚起來

It is a rather formal, slightly political-sounding word.

It is這是 a rather formal一個相當正式 slightly political-sounding word帶點政治味的詞

Though actually, in older communist-party English, cadre was also used for one official (a person, not a group), and newspapers still use it that way when they talk about party workers. In ordinary British or American English you are more likely to hear a cadre of experts meaning the small trained group.

Though actually不過事實上 in older communist-party English在早期共產黨用語的英語裡 cadre was also used for one official cadre也曾用來指一個官員 a person, not a group是一個人，不是一群人 and而 newspapers新聞媒體 when they talk about party workers講到黨務人員時 still use it that way還是這樣用 In ordinary British or American English在一般英式或美式英語裡 you are more likely to hear你比較會聽到的是 a cadre of experts a cadre of experts（一小群專家） meaning指的是 the small trained group那一小群受過訓練的人

It is not a word for a random bunch of friends.

It is not a word它不是用來形容 for a random bunch of friends一群隨便湊在一起的朋友