CHALLENGING

Definition:

1. [adjective] requiring full use of your abilities or resources; "ambitious schedule"; "performed the most challenging task without a mistake"
   Synonyms: ambitious
   
   
2. [adjective] stimulating interest or thought; "a challenging hypothesis"; "a thought-provoking book"
   Synonyms: thought-provoking
   
   
3. [adjective] disturbingly provocative; "an intriguing smile"
   Synonyms: intriguing
   
   

Synonyms:

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