Is it ensure, insure, or assure?
early 15c., from Middle French dénudation, from Latin denudationem (nominative denudatio), noun of action from past participle stem of denudare (see denude). Figurative use is from 1590s. In geology, from 1811.
denudation de·nu·da·tion (dē'nōō-dā'shən, -nyōō-, děn'yu-)
The removal of a covering or surface layer.