Burdensome \Bur"den*some\, a. Grievous to be borne; causing uneasiness or fatigue; oppressive. The debt immense of endless gratitude So burdensome. --Milton. Syn: Heavy; weighty; cumbersome; onerous; grievous; oppressive; troublesome. -- {Bur"den*some*ly}, adv. -- {Bur"den*some*ness}, n.