Is it ensure, insure, or assure?
also moth-ball, moth ball, "naphthalene ball stored among fabrics to keep off moths," 1891, from moth + ball (n.1).
1902 in a literal sense (to store away with mothballs), from mothball (n.); figurative sense from 1901.
To take something out of active use and preserve it for the future, as clothing is stored with mothballs: ''It's really sad to see Buran on the ground.'' It was used in 1988 and then mothballed (1949+)