irrational

不合理な、理屈に合わない

筋の通った考えや納得できる理由に基づいていない。

やさしい英語で： Not based on clear thinking or good reasons.

• I have an irrational fear of birds.
• His anger made him behave in irrational ways.
• Buying another car would be completely irrational.

類義語： unreasonable, illogical, senseless

反対語： rational, logical

よく使う表現： irrational fear, irrational behaviour, irrational decision

無理数の

二つの整数の割り算では表せない数についていう。

やさしい英語で： A number that cannot be written as one whole number divided by another.

• Pi is an irrational number.
• The square root of two is irrational.
• An irrational number has a decimal expansion that never ends or repeats.

反対語： rational

よく使う表現： irrational number, irrational root, irrational value