add-on

American  

[ad-on, -awn] / ˈædˌɒn, -ˌɔn /

noun

1. a device or unit added to equipment or a construction.

   an add-on to a computer;

   a nice add-on to an old house.

2. an extra charge.

   Add-ons for taxes and tour guide fees boosted the price of the vacation to $2,500.

3. an additional item, as a rider or provision.

   This is just another legislative add-on.

4. anything added on.

   Our sable faux fur vest is an easy add-on for dressy or casual occasions.

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adjective

1. being installed or provided as an add-on.

   Add-on packs for this game are just a few dollars.

add-on British  

noun

1. a feature that can be added to a standard model or package to give increased benefits

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Etymology

Origin of add-on

First recorded in 1945–50; noun and adj. use of verb phrase add on

Example Sentences

“What’s going to be next? An add-on for access to the bathroom?” she said.

From MarketWatch • Apr. 10, 2026

Still, some travelers hope that if enough consumers balk at paying add-on fees by opting for fewer extras or by forgoing air travel altogether, airlines may eventually walk those fees back — to some degree.

From MarketWatch • Apr. 10, 2026

Guests can purchase tickets to the hour-long Superman Experience: Defenders Unite as a stand-alone attraction or as an add-on to the Warner Bros.

From Los Angeles Times • Apr. 9, 2026

Starting April 1, a new add-on fee of $200 will be charged, up from the $149 customers paid in March, according to Cathay’s website.

From The Wall Street Journal • Apr. 1, 2026

We sat on opposite ends of the sofa in the add-on living room.

From "Silent To The Bone" by E.L. Konigsburg

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