late 14c., from Latin obsecrationem (nominative obsecratio) "a beseeching, imploring, supplication, entreaty," noun of action from past participle stem of obsecrare "to beseech, entreat" (on religious grounds), from ob- (see ob-) + sacrare "to make or declare sacred" (see sacred).[obsecration etymology, obsecration origin, 英语词源]