Difficult : needing much effort or skill to accomplish, deal with, or understand.Awesome ; extremely impressive or daunting; inspiring awe.Burdensome : difficult to carry out or fulfil; taxing.Dutiful : conscientiously or obediently fulfilling one's duty.Onerous : (of a task or responsibility) involving a great deal of effort, trouble, or difficulty.Synonym of Onerous is Burdensome