Is it ensure, insure, or assure?
fem. proper name, from French Jeanne, Old French Jehane, from Medieval Latin Johanna (see John). As a generic name for "girl, girlfriend" it is attested from 1906 in U.S. slang. Never a top-10 list name for girls born in the U.S., it ranked in the top 50 from 1931 to 1956. It may owe its "everywoman" reputation rather to its association with John.