onerous

tarea onerosa

describes a piece of work that is very demanding or tedious

una tarea que es difícil y desagradable de hacer

describes a heavy and difficult load or responsibility

responsabilidad onerosa

describes the state of being accountable for something very difficult

describe el estado de ser responsable de algo muy difícil

deber oneroso

describes a moral or legal obligation that is very difficult to perform

describe una obligación moral o legal que es muy difícil de cumplir