Denshi Jisho — Online Japanese dictionary

難しい むずかしい 1: difficult; hard; troublesome; complicated; serious (disease, problem, etc.);
2: fussy; particular; fastidious; hard to please; displeased;
3: gloomy; glum; sullen; serious (look);
4: (Archaism) dirty; unclean; filthy; detestable;
5: (Archaism) unpleasant; uncomfortable; creepy; spooky
Common word, Adjective 
難しい むつかしい 1: difficult; hard; troublesome; complicated; serious (disease, problem, etc.);
2: fussy; particular; fastidious; hard to please; displeased;
3: gloomy; glum; sullen; serious (look);
4: (Archaism) dirty; unclean; filthy; detestable;
5: (Archaism) unpleasant; uncomfortable; creepy; spooky
Adjective 
難しい病気 むずかしいびょうき serious disease
Noun 

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