imaginary

adjective
UK /ɪˈmædʒ.ɪ.nər.i/
US /ɪˈmædʒ.ə.ner.i/

Something imaginary is not real and only exists in your mind.

My little sister has an imaginary friend who sits with her at lunch.


OTHER MEANINGS

2. Existing only in a story or made-up world.

The dragon in the book lives in an imaginary kingdom.

3. A number in math that involves the square root of a negative number.

In math class we learned about imaginary numbers like the square root of minus one.

4. Something that is not actually there but seems to be.

The scary shadow on the wall was just an imaginary monster.