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Idioms about inside

    inside of, Informal. within the space or period of: Our car broke down again inside of a mile.
    inside out,
    1. with the inner side reversed to face the outside.
    2. thoroughly: completely: She knew the work inside out.

Origin of inside

First recorded in 1350–1400; Middle English; see origin at in, side1

synonym study for inside

7. 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.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


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.

Where does inside come from?

The first records of the term inside come from the mid-1300s. It combines the terms in, which is used to indicate inclusion within something, and side, referring to a surface of something.

Inside has some slang uses as well. If you want to say someone is in prison, you can say they are inside. But a person on the inside refers to someone in a position of power within a group who is secretly loyal or helpful to someone who is not part of that group. Inside information is information known only to those within an organization that outsiders are not supposed to know.

The phrase inside out refers to something whose insides are now facing out, such as with a sock. But if you know something inside out, you know something completely. You know both its external portions and structure and its inner, complex workings. If you keep studying the dictionary, you’ll eventually know words inside out and be a language insider!

Did you know … ?

What are some other forms related to inside?

What are some synonyms for inside?

What are some words that share a root or word element with inside

What are some words that often get used in discussing inside?

How is inside used in real life?

Inside is a very common word with several meanings.


Try using inside!

Which of the following is NOT a synonym for inside?

A. interior
B. innards
C. outside
D. indoors

How to use inside in a sentence

British Dictionary definitions for inside

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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Idioms and Phrases with inside


The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.