Formal term for matters of great importance or urgency. Often used in official or serious contexts.
This is an urgent matter.
緊要の課題に取り組む。
Tackle a vital task.
key terrain
Standard kanji form. Used in formal and written contexts.
Kana spelling is acceptable, especially in less formal writing or when the kanji are considered difficult.
Compound of 緊 (urgent, tense) and 要 (essential, need). The combination conveys something both urgent and essential.