Mothballs are small balls of chemical pesticide and deodorant used when storing clothing and other articles susceptible to damage from mold or moth larvae. They come in two different formulations, one using naphthalene and the other using paradichlorobenzene as the active ingredient.
Their use when clothing is stored out-of-season gave rise to the colloquial use of the term mothballed to refer to anything which is put into storage or whose operation is suspended.