Transformer

Transformer is a device employing the principle of mutual induction to convert variations of current in a primary circuit into variations of voltage and current in a secondary circuit.
Transformer is a piece of electrical equipment to convert
electric power from one voltage to another.

Transformeran electric device consisting essentially of two or more windings wound on the same core, which by electromagnetic induction transforms electric energy from one set of one or more circuits to another set of one or more circuits such that the frequency of the energy remains unchanged while the voltage and current usually change.

Sources:

Словник Webster's Dictionary https://www.merriam-webster.com/

Nick Brieger, Alison Pohl: Technical English Vocabulary and Grammar

Англійський словник Коллінза, електронний ресурс: https://www.collinsdictionary.com/