figment
noun uk/ˈfɪɡ.mənt/ us/ˈfɪɡ.mənt/
a figment of someone's imagination 凭空想象的事物，臆造的东西
something that seems real but is not
Was it just a figment of my imagination or did I hear John's voice in the other room? 是我的想象还是我真听到了约翰在另一间房里说话？