Inherited from Old Galician-Portuguese sẽara, from Iberian Vulgar Latin senara, from Paleo-Hispanic, ultimately from Proto-Celtic *senara (“piece of land cultivated on the side”), from *sen- (“separation”) (< Proto-Indo-European *swé (“self”)) + *aryeti (“to plow”).
Cognate with Galician seara, senra, Mirandese senara, Asturian senra and Spanish serna.