/ stjuːˈpendəs; NAmE stuː-/ adjective
extremely large or impressive, especially greater or better than you expect
SYN staggering :
stupendous achievements
stupendous costs
► stu·pen·dous·ly adverb
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WORD ORIGIN
mid 16th cent.: from Latin stupendus to be wondered at (gerundive of stupere ) + -ous .