a figment of someone's imagination
US /ə ˈfɪɡmənt əv ˈsʌmwʌnz ɪˌmædʒɪˈneɪʃən/
UK /ə ˈfɪɡmənt əv ˈsʌmwʌnz ɪˌmædʒɪˈneɪʃən/

1.
khayalan imajinasi seseorang, rekaan semata
something that someone has imagined and that does not really exist
:
•
The monster under the bed was just a figment of his imagination.
Monster di bawah tempat tidur hanyalah khayalan imajinasinya.
•
Her fear of flying is not a figment of her imagination; it's a real phobia.
Ketakutannya akan terbang bukanlah khayalan imajinasinya; itu adalah fobia nyata.