Tantamount

/ˈtæntəˌmaʊnt/ adjective medium

Equivalent in effect or value to something else, even if not identical in form.

Refusing to answer the question was tantamount to admitting he had made the mistake.

Memory Trick

Break the word into 'tant' (as much) plus 'amount' -- something tantamount amounts to exactly the same thing as whatever it is being compared to.