effective

American  

[ih-fek-tiv, ee-fek‐] / ɪˈfɛk tɪv, iˈfɛk‐ /

adjective

1. adequate to accomplish a purpose; producing the intended or expected result.

   effective teaching methods; effective steps toward peace.

   Synonyms:

   competent, capable

   Antonyms:

   useless, futile

2. actually in operation or in force; functioning.

   The law becomes effective at midnight.

3. producing a deep or vivid impression; striking.

   an effective photograph.

4. prepared and available for service, especially military service.

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noun

1. a member of the armed forces fit for duty or active service.

2. the effective total of a military force.

effective British  

/ ɪˈfɛktɪv /

adjective

1. productive of or capable of producing a result

2. in effect; operative

   effective from midnight

3. producing a striking impression; impressive

   an effective entrance

4. (prenominal) actual rather than theoretical; real

   the effective income after deductions

5. (of a military force, etc) equipped and prepared for action

6. physics (of an alternating quantity) having a value that is the square root of the mean of the squares of the magnitude measured at each instant over a defined period of time, usually one cycle See also root mean square

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noun

1. a serviceman who is equipped and prepared for action

Usage

What are other ways to say effective? The adjective effective describes things that are adequate to accomplish a purpose, or that produce the intended or expected result. But effective isn’t quite the same as effectual, efficacious, or efficient! Find out why on Thesaurus.com.

Related Words

operative. telling.

Other Word Forms

• effectively
  adverb
• effectiveness
  noun
• effectivity
  noun
• preeffective
  adjective
• quasi-effective
  adjective
• subeffective
  adjective
• supereffective
  adjective
• uneffective
  adjective

Etymology

Origin of effective

First recorded in 1350–1400; Middle English from Latin effectīvus “practical,” equivalent to effect(us), past participle of efficere ( see effect) + -īvus adjective suffix ( see -ive)

Explanation

If your email outlining a plan to reduce office paper waste resulted in a 20 percent reduction in paper use, that means your plan was effective: it did what you wanted it to do. The adjective effective has many shades of meaning, but you'll usually see it describing something that's able to produce a desired goal. Effective traces back to the Latin word effectivus, from efficere, meaning “work out, accomplish,” and that meaning still holds true. Something effective gets the job done. As President, hopefully your policies are effective. We also use effective for something real and in effect, like the effective price of gas, or your effective grounding.

Example Sentences

While effective in some cases, those changes can carry risks because they are difficult to reverse if unintended side effects occur.

From Science Daily • May 25, 2026

RAND: The primary reason the model is effective is its ability to come up with lots of relevant facts and evidence, and then explain it in a clear, easily understandable way.

From The Wall Street Journal • May 24, 2026

But he also said polling hasn’t shown that message to be an effective one, and he’s confident that voters will show their ongoing trust in the party at the polls.

From Los Angeles Times • May 24, 2026

Republicans currently control both chambers of Congress, with a 53-47 effective majority in the Senate and a narrow edge in the House.

From MarketWatch • May 23, 2026

This method was particularly effective in the case of the dragon of Lambton Hall.

From "Jeremy Thatcher, Dragon Hatcher" by Bruce Coville

Related Words

• active
• adequate
• compelling
• competent
• direct
• efficient
• forceful
• impressive
• potent
• powerful
• practical
• successful
• useful
• valid