Is it ensure, insure, or assure?
1819, "work-room of a sculptor or painter," from Italian studio "room for study," from Latin studium (see study). Motion picture sense first recorded 1911; radio broadcasting sense 1922; television sense 1938. Studio apartment first recorded 1903.
[fr stud or studhorse, ''stallion, esp one kept for breeding,'' the term found by 1903; first sense popularized by 1940s jive talk]