under

/ˈʌndər/
preposition
  1. In or to a position below or beneath something.
    • The cat is hiding under the bed.
    • She found her keys under a pile of papers.
    • We sat under a large tree to escape the sun.
  2. Less than a particular age, amount, or level.
    • The project cost under a thousand dollars.
    • Temperatures will stay under 30 degrees today.
    • Children under five enter the museum for free.
  3. Controlled or affected by a particular condition, authority, or influence.
    • The building is under construction.
    • He is under a lot of pressure at work.
    • The country was under military rule for a decade.
  4. Using a particular name or category.
    • You can find the information under 'help' in the menu.
    • The book is filed under 'fiction' in the library.
    • She writes under a pen name.
Antonyms
adverb
  1. In or to a lower position or state.
    • The diver stayed under for over a minute.
    • He pushed the box under to hide it.
    • The ship went under after hitting the iceberg.
adjective
  1. Located below or beneath something.
    • The under part of the car is rusty.
    • The under layer of the cake is chocolate.
    • Check the under side of the leaf for insects.