There are a few different synonyms for the word "aerotrains." One possibility could be "hovertrains," which refers to trains that travel using magnetic levitation technology to hover above the ground. Another option could be "monorails," which are trains that use a single rail to travel above the ground. Additionally, the term "maglev trains" could be used, which stands for "magnetic levitation trains" and refers to trains that use powerful electromagnets to hover above a guideway and travel at high speeds. Finally, "transrapid trains" refers to a particular type of maglev train technology that was developed by the German engineering company Siemens.