big job; great task; major undertaking
Refers to a task or project that is large in scale, importance, or difficulty. Often implies a significant commitment of time and effort.
Renovating the house is a big job.
He's nervous because he's been entrusted with a major task.
大役 focuses on an important role or duty assigned to a person, whereas 大仕事 emphasizes the scale of the work itself.
Compound of 大 (おお, 'big') + 仕事 (しごと, 'work, job').