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.

Synonym Usage

operative. telling.

Other Word Forms

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

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

See Examples For:

effective

Officials said that, effective Sept. 8, or the day after Labor Day, Canada plans to place tariffs ranging between 15% and 50% on about $20 billion of goods, or roughly 7% of total U.S. imports.

From The Wall Street Journal ● Aug. 26, 2026

"So, if indigo light can suppress myopia in these tests, then it should also be quite effective in humans."

From Science Daily ● Aug. 26, 2026

Professor Gemma Sharp said the study was going to be "a real game changer" for menstrual health research and could cut waiting times for effective treatment.

From BBC ● Aug. 26, 2026

Canadian Prime Minister Mark Carney said retaliatory tariffs would be effective September 8, as analysts warn of tit-for-tat escalation.

From Barron's ● Aug. 25, 2026

Sarah was still studying Mrs. Ebeling as if the secrets of the universe, or at least of our family, could be found by determining the most effective manner of bringing groceries into the house.

From "Liar, Liar" by Gary Paulsen

Related Words

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