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• plug-in
  plug-in

  adjective

  capable of or designed for being connected to an electrical power source by plugging in or inserting: a plug-in transistor.
• plug in
  plug in

  verb

  (tr, adverb) to connect (an electrical appliance) with a power source by means of an electrical plug

plug-in

American  

[pluhg-in] / ˈplʌgˌɪn /

adjective

1. capable of or designed for being connected to an electrical power source by plugging in or inserting: a plug-in transistor.

   a plug-in hair dryer;

   a plug-in transistor.

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noun

1. plug.

2. jack.

3. a plug-in appliance.

4. Computers. a small software program that builds additional functionality into a stand-alone computer application.

   Your web browser can’t display this video without a plug-in.

plug in British  

verb

1. (tr, adverb) to connect (an electrical appliance) with a power source by means of an electrical plug

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noun

1. a device that can be connected by means of a plug

2. computing a module or piece of software that can be added to a system to provide extra functions or features, esp software that enhances the capabilities of a web browser

3. computing ( as modifier )

   plug-in memory cards

plug-in Scientific  

/ plŭg′ĭn′ /

1. An accessory software or hardware package that is used in conjunction with an existing application or device to extend its capabilities or provide additional functions.

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Etymology

Origin of plug-in

First recorded in 1920–25; adjective and noun use of verb phrase plug in

Example Sentences

China’s auto market weakened further in May, with rising oil prices denting demand for gasoline-powered cars and helping electric and plug-in hybrid vehicles capture a record share of new car sales.

From The Wall Street Journal • Jun. 8, 2026

Fully-electric cars comprised 23% of all cars sold and plug-in hybrid models accounted for 25%.

From The Wall Street Journal • Jun. 3, 2026

Forecast for the percentage of 2026 global sales of electric vehicles and plug-in hybrid cars, from 25% in 2025.

From Barron's • May 22, 2026

The joint venture would take responsibility for the sale and distribution of Dongfeng’s Voyah-branded NEVs, a category that includes fully electric variants and plug-in hybrids.

From The Wall Street Journal • May 21, 2026

You may think that music is a luxury, a plug-in to make human life more enjoyable.

From "The Story of Music" by Howard Goodall

Related Words

• factor
• ingredient
• item
• peripheral
• piece
• segment
• unit