inside

American  

[in-sahyd, in-sahyd, in-sahyd, in-sahyd, in-sahyd, in-, in-sahyd] / ˌɪnˈsaɪd, ˈɪnˌsaɪd, ˌɪnˈsaɪd, ˈɪnˈsaɪd, ˌɪnˈsaɪd, ˈɪn-, ˈɪnˌsaɪd /

preposition

1. on the inner side or part of; within: inside the envelope.

   inside the circle;

   inside the envelope.

2. prior to the elapse of; within.

   He promised to arrive inside an hour.

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adverb

1. in or into the inner part.

   Please go inside.

2. indoors.

   They play inside on rainy days.

3. within one's heart, reason, etc.; by true nature; fundamentally.

   I know inside that he's not guilty.

   Inside, she's really very shy.

4. Slang. in prison.

noun

insides plural

1. the inner or internal part; interior.

   the inside of the house.

   Antonyms:

   exterior, outside

2. the inner side or surface: He pinned the money to the inside of his jacket.

   the inside of the hand;

   He pinned the money to the inside of his jacket.

3. insides.

4. a select or inner circle of power, prestige, etc..

   a man on the inside.

5. the shortest of several parallel, curving tracks or lanes; the part of an oval track closest to the inner rail.

   The horse came up fast on the inside.

6. the inward nature, mind, feelings, etc.

7. Slang. confidential or secret information.

8. an inside passenger or place in a coach, carriage, etc.

adjective

1. situated or being on or in the inside; interior; internal.

   an inside seat.

2. acting, employed, done, or originating within a building or place.

   He used to work on the dock but now he has an inside job.

3. derived from the inner circle of those concerned in and having private knowledge of a situation.

   inside information.

4. Baseball. (of a pitched ball) passing between home plate and the batter.

   The pitch was low and inside.

idioms

1. inside of, within the space or period of.

   Our car broke down again inside of a mile.

2. inside out,

   1. with the inner side reversed to face the outside.

   2. thoroughly: completely.

      She knew the work inside out.

inside British  

noun

1. the interior; inner or enclosed part or surface

2. the side of a path away from the road or adjacent to a wall

3. informal (also plural) the internal organs of the body, esp the stomach and bowels

4. in a period of time less than; within

5. with the inside facing outwards

6. to know something thoroughly or perfectly

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preposition

1. in or to the interior of; within or to within; on the inside of

adjective

1. on or of an interior; on the inside

   an inside door

2. (prenominal) arranged or provided by someone within an organization or building, esp illicitly

   the raid was an inside job

   inside information

adverb

1. within or to within a thing or place; indoors

2. by nature; fundamentally

   inside, he's a good chap

3. slang in or into prison

inside More Idioms  

More idioms and phrases containing inside

• on the inside
• step in (inside)

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Usage

What does inside mean? Inside means on the inner side of something, such as a box or your refrigerator. Inside designates physical space, like the interior of a book, but it can also be used in situations about time. If your teacher tells the class that you need to finish the test inside of an hour, they mean you need to finish it in less than, or within, an hour. When the hour has gone by, you have to be done the test. Inside can be used to mean indoors, as in Because it rained, we were stuck inside during our vacation. Inside can also be used to describe the position of something. For example, an inside wall refers to the face of a wall that faces the interior of a building. The inside of something is its interior. The inside of a house is the interior, while your insides is everything beneath the skin, such as your skeleton and organs. Example: The inside of the building was sleek and modern, while the outside looked like an old church.

Synonym Usage

Inside, interior both refer to the inner part or space within something. Inside is a common word, and is used with reference to things of any size, small or large: the inside of a pocket. Interior, somewhat more formal, denotes the inner part or the space or regions within; it usually suggests considerable size or extent, and sometimes a richness of decoration: the interior of a country, of the earth, of a cathedral.

Other Word Forms

Noun Inflected Forms

• insides
  plural

Etymology

Origin of inside

First recorded in 1350–1400; Middle English; see origin at in, side ¹

Explanation

Something that's inside is located near the center or in the interior of a space. The inside of a perfectly baked potato should be fluffy, buttery, warm, and delicious. You can scrape inside a jar with a knife to get the last of the jam, or stay inside the house all day when it's very hot outside. Inside can serve as an adjective, noun, or adverb, depending how you use it, but it always refers to the inner, most privileged, or deepest part of something. Colloquially, your insides are your digestive system or stomach, and when someone's inside after stealing a car, they're in prison.

Example Sentences

See Examples For:

inside insides

The Air Force hasn’t disclosed the medical facilities inside the Qatari aircraft.

From The Wall Street Journal ● Aug. 2, 2026

"The 10-year-old Emma is screaming inside about what is going on. I don't think it'll sink in probably until the next Commonwealth Games."

From BBC ● Aug. 2, 2026

Instead, the breaks clustered inside genes controlled by super-enhancers.

From Science Daily ● Aug. 2, 2026

Zeldin appears to be following John Oliver’s adage that if you want to do something harmful, “put it inside something boring” to avoid public scrutiny.

From Slate ● Aug. 2, 2026

Everything she owns fits inside a paper bag, which she carries with her as she boards the USS General John Pope, a US Navy ship, in Manila.

From "At Last She Stood" by Erin Entrada Kelly

Ingredients that I once felt so much shame around now grace the insides of my refrigerator.

From Salon ● Jun. 7, 2026

Instead, the team at the Field Museum used CT scans to take thousands of X-ray images, then compiled them to make a 3D model of the octopus, revealing its insides.

From Barron's ● May 25, 2026

Security cameras pointed to the insides of the walls rather than the outside.

From The Wall Street Journal ● Dec. 23, 2025

"Hunger is not something you can ignore or put out of your mind, it gnaws at your insides with increasing intensity," she continued, adding that hunger is particularly disruptive for children.

From BBC ● Nov. 19, 2025

My insides felt like they were going to burst.

From Each Little Bird That Sings by Deborah Wiles

Related Words

• innards
• interior