'sosiego' originates from Spanish, specifically from the Old Spanish noun/verb related to 'sosegar' (to calm).

'sosiego' developed in Old Spanish from the verb 'sosegar' (Old Spanish forms like 'sosegare/soseggo'), which in turn traces back to Late Latin formations combining elements related to 'sedare' (Latin: 'to calm, settle') with a prefixed element.

Initially connected to the verbal sense 'to calm' or 'to cause calm,' it evolved into the nominal sense denoting the 'state of calm or tranquility' now expressed by 'sosiego'.