mono·rail 
/ˈmɑ:nəˌreɪl/ noun
plural mono·rails /ˈmɑ:nəˌreɪl/ noun : a type of railroad that uses a single track which is usually high off the ground [count] ▪ Monorails connect different parts of the park. [noncount] ▪ traveling by monorail ; also [count] : a vehicle that travels on a monorail
▪ The passengers boarded the monorail.
▪ The passengers boarded the monorail.
