na-adjective, noun
eventful; full of incidents; hectic
A yojijukugo describing a situation or period that is busy, eventful, or filled with various matters. Often used in formal or written contexts.
今年は多事多端な一年だった。
This year was an eventful one.
多事多端の折、ご自愛ください。
Please take care of yourself during this busy time.
多端 is a noun meaning 'many matters' or 'multifariousness', often used in the phrase 多端な; 多事多端 combines both concepts for a stronger effect.
A yojijukugo composed of 多事 (many events) and 多端 (many matters), both meaning 'many things happening', reinforcing the idea of busyness and eventfulness.