autotransformer
C2Գոյական/US /ˈæʌtɑtrænsfɔrmər/ AUTOTRANSFORMER; UK /ˈæʌtɑtrænsfɔrmər/ AUTOTRANSFORMER/
A transformer in which part of the primary winding is used as a secondary winding, or vice versa; -- called also a compensator or balancing coil.
