laborious
adj. C1 Advanced US //ɫəˈbɔɹiəs// UK //lɐbˈɔːɹɪəs// la·bo·ri·ous
adj. describing a task that is very tiring, difficult, or takes a long time to finish. You use this when something requires a lot of hard work.
adj. requiring great physical or mental effort; tedious and exhausting. Often used to describe processes that are slow or involve repetitive, difficult tasks.
The manual data entry was a laborious task.
The researchers spent several months on a laborious process of cross-referencing every single document in the archive.
While the initial concept was simple, the execution proved laborious, requiring the team to manually verify thousands of data points before the final report could be published.
From Old French laborios, from Latin laboriosus. By surface analysis, labor + -ious