essential

不可欠な、必要な

それがないと物事が成り立たない、または成功しないほど必要な。

やさしい英語で： Needed so much that something cannot happen or succeed without it.

• Water is essential for life.
• A helmet is essential when you ride here.
• It is essential that everyone arrives on time.

使い方： essential for something (Clean water is essential for health.); essential to something (Trust is essential to a strong friendship.); it is essential to do something (It is essential to check the brakes before leaving.)

類義語： necessary, vital, indispensable

反対語： unnecessary, optional

よく使う表現： essential for something, essential equipment, absolutely essential

重要な

物事の中心となる、またはとても大切な。

やさしい英語で： Very important or central to something.

• Music plays an essential role in the film.
• The garden is an essential part of the house’s charm.
• Her warmth was an essential element of her appeal.

類義語： important, key, central

反対語： unimportant

よく使う表現： essential role, essential element, essential part

本質的な、根本的な

物事の最も基本的な性質や特徴に関わる。

やさしい英語で： Belonging to the most basic nature or character of something.

• Its essential nature has not changed.
• The two stories share the same essential features.
• What is the essential difference between these approaches?

類義語： fundamental, basic, underlying

反対語： superficial

よく使う表現： essential nature, essential character, essential difference

本態性の、特発性の

原因がわかっていない病気や症状を表す。

やさしい英語で： Describing a medical condition that has no known cause.

• The doctor diagnosed essential hypertension.
• Essential tremor can make writing difficult.
• She takes medication to control her essential tremor.

類義語： idiopathic

よく使う表現： essential hypertension, essential tremor, essential blepharospasm