Herculean task; next-to-impossible undertaking
Describes a task or feat that is extremely difficult, almost impossible to achieve.
Solving this difficult problem is a Herculean task.
He accomplished a next-to-impossible undertaking.
Standard kanji spelling using 業 (わざ).
Alternate spelling using 技 (わざ), also seen.
至難 (extremely difficult) + の (possessive particle) + 業/技 (task, feat). The phrase literally means 'a task of extreme difficulty'.