What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
1Electricity. Designating a modified state of an electrical conductor when subjected to a magnetic field. Now historical.
2Physiology. Of, relating to, or characterized by electrotonus.
Mid 19th century; earliest use found in Michael Faraday (1791–1867), natural philosopher, scientific adviser, and Sandemanian. From electro- + tonic.