espalda (de un ser humano), lomo (de un animal); respaldo (de una silla), espalda (de ropa); reverso, dorso, revés; fondo, parte de atrás; defensa (en deportes)
Ejemplos de uso de
back
noun
•She was carrying her little daughter on her back.
•She has a pain in the small of her back.
•I slapped him on his back to congratulate him.
•She stabbed him in the back.
•He was handcuffed with his hands behind his back.
Back up significa respaldar > The soldiers backed up their captain when the army accused him of treason.Back up también significa retroceder > He tried to back up his car in the busy road.