The term 'coil (electrical device)' can be summarized by the crossword solution 'Tesla'. Nikola Tesla was a Serbian-American inventor and engineer who is best known for his contributions to the design of the modern alternating current (AC) electricity supply system. He also developed the Tesla coil, an electrical resonant transformer circuit used to produce high-voltage, low-current, high-frequency alternating-current electricity. The Tesla coil is still used today in radio and television sets and other electronic equipment.