in·side (ĭn-sīd, ĭnsīd′)
a. An inner or interior part.
b. Inward character, perceptions, or feelings: felt good on the inside about volunteering to help.
2. An inner side or surface.
3. The part away from the edge; the middle part.
4. insides Informal
a. The inner organs; entrails.
b. The inner parts or workings: the insides of a TV set.
5. Slang Confidential or secret information.
1. Inner; interior.
2. Relating to, known to, or coming from an exclusive group: inside information; an inside joke.
3. Baseball Passing on the side of home plate nearer the batter. Used of a pitch.
1. Into or in the interior; within.
2. On the inner side.
3. Slang In prison.
1. Within: We'll be there inside an hour.
a. On the inner side or part of: inside the package.
b. Into the interior of: going inside the house.
1. With the inner surface turned out; reversed: wore the sweatshirt inside out.
2. Informal As completely as possible; thoroughly: knew the city inside out.
on the inside
In a position of confidence or influence.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.