艰难(jiān nán) - arduous, hard, tough going in Mandarin

艰难 (jiān nán) describes something that is hard going: a stretch of life, a journey, a decision, a movement made by a body that is struggling. It carries weight and a touch of suffering.

Use it as an adjective before a noun with 的, or turn it into an adverb with 地 to say that an action was performed with difficulty. 他艰难地爬上山 means he climbed the mountain with real effort.

The English-speaker trap is treating 艰难 and 难 as swappable. 难 is the everyday word for difficult, and covers exam questions, recipes and Chinese grammar. 艰难 is heavier and more literary, and it is about hardship endured rather than a puzzle you cannot solve. Saying 这道题很艰难 for a tricky maths problem sounds melodramatic; 很难 is what you want.