心臓部

(1)a small group of indispensable persons or things; "five periodicals make up the core of their publishing program"

(2)どうしても欠かせない人や物の小グループ

(3)the choicest or most essential or most vital part of some idea or experience; "the gist of the prosecutor's argument"; "the heart and soul of the Republican Party"; "the nub of the story"

(4)何らかの考えや経験の中から選り抜きで、最も不可欠でまた最も重要な部分

(1)