backside

s. trasero, asentaderas

respaldo | dorso | parte posterior | cara posterior | parte trasera | cara trasera

culo, espalda, rabel, trascorrar, trasero, traspontín, trastienda

(n.) = parte posterior, parte de atrás
Ex: The backside of a historical document can reveal interesting details about the document's history as an artifact.

(n.) = culo, trasero
Ex: Corporal punishment, the act of disciplining students by inflicting physical pain (usually paddling the child's backside), has recently come under fire due to the public's growing concern over child abuse.
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* sit on + Posesivo + backside = rascarse la barriga, rascarse los huevos