What is the difference between (internal, interior, indoor, inner & inside) in their meanings?


Internal - Inner - Indoor - Interior

The words internal, interior, indoor, inner and inside have very similar meanings.

As you might see, all of them start with the word IN.
IN usually refers to a location around which there is some sort of boundary. For example:

  • in the city = not outside the boundaries of the city
  • in the kitchen = not outside the boundaries of the kitchen
  • in the world = not outside this world

Read the examples below carefully and pay attention to the context in which each word is used. Also, notice thatadjectives are always used before nouns.

INSIDE (preposition)
within the limits/boundaries of something
opposite : outside

  • He might look tall and strong, but inside of him, there is a 5-year-old craving attention.
  • You don’t know what goes on inside his mind.

INSIDE (adverb)
towards or in an enclosed area

  • Why don’t we go inside and have a cup of tea? My brother must be eavesdropping behind the trees.
  • No, I’m sure he’s inside. Let’s stay outside.

INSIDE (adjective)
done by somebody who is part of a group / not the outside part of something

  • How did the robbers know what time the guard had lunch?
  • They must have had some inside information.
  • I always keep a small knife with me in an inside pocket.

INSIDE (noun)
the inner part of something

  • The inside of a watermelon is green while the outside is red.
  • No, you’re wrong! The inside is red and the outside is green.

INTERNAL (adjective)
connected with the inside of something
opposite : external

  • I’ve painted all our internal doors canary yellow.
  • What did your husband have to say about it?
  • Oh, he loved it. He painted the external doors purple.

INNER (adjective)
near or in the centre of something
opposite : outer

  • Mary might not be the prettiest girl around, but her inner beauty shines through.
  • Why don’t you ask her out?
  • She lives in inner London and I wouldn’t like to spend hours travelling to meet her.

INDOOR (adjective)
situated in a building
opposite : outdoor

  • I’d love to have an indoor swimming-pool, but our house is too small for that.

the inside part of a car or a building
opposite : exterior

  • I like the interior of his house, but the exterior is a bit strange with all those pink flowers painted on the walls.

INTERIOR (adjective)
connected with the inside part of something

  • Are there no flowers painted on the interior walls?
  • No, he had all the interior walls painted white.


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