1swiv·el 
/ˈswɪvəl/ noun
plural swiv·els /ˈswɪvəl/ noun [count] : a device that joins two parts so that one of the parts can turn or spin while the other part does not move
▪ The gun was mounted on a swivel. ▪ a swivel chair [=a chair with the seat mounted on a swivel so that it turns freely]
▪ The gun was mounted on a swivel. ▪ a swivel chair [=a chair with the seat mounted on a swivel so that it turns freely]
