a. [ F. tant so much (L. tantus) + E. amount. ] Equivalent in value, signification, or effect. [ 1913 Webster ]
A usage nearly tantamount to constitutional right. Hallam. [ 1913 Webster ]
The certainty that delay, under these circumstances, was tantamount to ruin. De Quincey. [ 1913 Webster ]
v. i. To be tantamount or equivalent; to amount. [ Obs. ] Jer. Taylor. [ 1913 Webster ]