effective

効果的な、有効な

うまく働いて、望む結果をもたらす。

やさしい英語で： Something that works well and gives the result you want.

• This is an effective treatment for headaches.
• Their new strategy was surprisingly effective.
• Which method is most effective for teaching beginners?

使い方： effective against something (This spray is effective against mosquitoes.); effective in doing something (The lessons were effective in improving her reading.)

類義語： successful, useful, efficient

反対語： ineffective

よく使う表現： effective treatment, effective method, effective against something, effective protection

有効な、施行中の

ある時点から正式に適用され、効力を持っている。

やさしい英語で： Officially applying or operating from a particular time.

• The new rules are effective immediately.
• The agreement became effective last month.
• What is the effective date of the change?

使い方： effective from a date (The contract is effective from the first of June.); effective on a date (The new policy becomes effective on Monday.)

類義語： in force, valid

よく使う表現： effective date, become effective, effective from monday

印象的な、効果的な

人の感情や考え、行動に強い影響を与える。

やさしい英語で： Having a strong effect on how people feel, think, or act.

• Her speech was brief but effective.
• The silence made the final scene especially effective.
• He delivered an effective argument that changed several minds.

類義語： powerful, persuasive, forceful

反対語： ineffective

よく使う表現： effective speech, effective ending, effective argument

事実上の、実質的な

公式に認められていなくても、実際に存在したり行使されたりする。

やさしい英語で： Actually present or held in practice, even without official recognition.

• The rebels had effective control of the town.
• She held effective power despite having no official title.
• The agreement gave workers effective control over hiring.

類義語： actual, de facto

よく使う表現： effective control, effective command, effective power

から、以降

示された時点から正式に適用されることを表す。

やさしい英語で： Starting officially at the time mentioned.

• Effective Monday, parking will be free.
• The company raised its prices effective yesterday.
• Effective next year, all students will receive free lunches.

使い方： effective + time (Effective tomorrow, the office will open at eight.)

類義語： as of, starting from

よく使う表現： effective immediately, effective tomorrow, effective next month