Is it ensure, insure, or assure?
1550s, "to give up as hopeless," from French déplorer (13c.), from Latin deplorare "deplore, bewail, lament, give up for lost," from de- "entirely" (see de-) + plorare "weep, cry out." Meaning "to regret deeply" is from 1560s. Related: Deplored; deploring.