Why was clemency trending last week?
1760, from Spanish hacienda "landed estate, plantation," earlier facienda, from Latin facienda "things to be done," from facere "to do" (see factitious). For noun use of a Latin gerundive, cf. agenda. The owner of one is a hacendado.
The change of Latin f- to Spanish h- is characteristic; e.g. hablar from fabulari, hacer from facere, hecho from factum, hermoso from formosum. Confusion of initial h- and f- was common in 16c. Spanish; the conquistador is known in contemporary records as both Hernando and Fernando Cortés.