1793, "a little box," from French cassette, from a diminutive of Old North French casse "box" (see case (n.2)). Meaning "magnetic tape cartridge" is from 1960.
"de-magnetize," originally especially of ships as a defense against magnetic mines, 1940, from de- + the name of German scientist Carl Friedrich Gauss (1777-1855), a pioneer in the study of magnetics.
"coil of insulated wire carrying an electrical current and having magnetic properties," 1827, from French solénoïde, from Greek sōlēnoeidēs "pipe-shaped," from sōlēn "pipe, channel" + combining form of eidos "form, shape" (see -oid). Related: Solenoidal.
1610s, "the characteristic properties of a magnet," from Modern Latin magnetismus (see magnet + -ism). Figurative sense of "personal charm, attractive power or influence" is from 1650s; in the hypnotic sense it is from Mesmer (see mesmerism). Meaning "science of magnets and magnetic phenomena" is by early 19c.