Is it ensure, insure, or assure?
late 14c., "act of dwelling; dwelling place," from Old French residence, from Medieval Latin residentia, from Latin residentem (nominative residens) "residing, dwelling," present participle of residere "reside" (see reside). Also borrowed into German (Residenz), Dutch (residentie).
residence res·i·dence (rěz'ĭ-dəns, -děns')
A medical residency.
in anthropology, the location of a domicile, particularly after marriage. Residence has been an important area of investigation because it is a locus where biological (consanguineal) and marital (affinal) forms of kinship combine.