অর্থ : Requiring full use of your abilities or resources.
							উদাহরণ : 
							Ambitious schedule.
							Performed the most challenging task without a mistake.
							
সমার্থক : ambitious
অর্থ : Stimulating interest or thought.
							উদাহরণ : 
							A challenging hypothesis.
							A thought-provoking book.
							
সমার্থক : thought-provoking