老大难

Traditional (Taiwan): 老大難

lǎodànán ㄌㄠˇ ㄉㄚˋ ㄋㄢˊ

    • chronic problem
    • long-standing difficult case

Character by character

Saying俗语俗語

Idiom惯用语 · In everyday use

Literally
old, big, difficult
Meaning
A problem that is complex and has gone unsolved for a long time, or a person or unit with such a problem. A "chronic problem."

Sources