What does 核 mean?
核 is a Japanese noun meaning “nucleus, kernel” in English. It can also be translated as “core (of an organization, team, etc.), nuclear weapons, nucleus (of an atom)” depending on context. It is written as 核 in kanji, かく in hiragana, and kaku in romaji. This word is part of JLPT N3 vocabulary.
Example sentence
この核時代にあっては、世界中どこの国だって安全ではない。
No country under the sun is safe in this nuclear age.