equivalent, as in value, force, effect, or signification:
His angry speech was tantamount to a declaration of war.
Origin
1635-45; adj. use of obsolete noun: that which amounts to as much, itself noun use of obsolete v.: to amount to as much < Anglo-Frenchtant amunter or Italiantanto montare to amount to as much. See tanto, amount
As a result, captive panda studies are of tantamount importance.
That's because a fully functioning ecology is tantamount to tangible wealth.
They trust each other with their careers, which among many academics is tantamount to trusting each other with their lives.
Inquiring into and articulating the factors that contribute to crime isn't tantamount to excusing it.
But whether society should treat immersion in video games as a risk tantamount to abusing drugs and alcohol is hotly debated.
Relocating them is tantamount to enabling them further.
For a rank amateur to accomplish a performance without breaking down in the vast finale was tantamount to a musical revolution.
But eating a baked potato is tantamount to eating a cupful of sugar.
For this reason, he has spent much of his time in conditions tantamount to solitary confinement.
Working in this radical new medium was tantamount to drawing in space.
British Dictionary definitions for tantamount
tantamount
/ˈtæntəˌmaʊnt/
adjective
1.
(postpositive) foll by to. as good (as); equivalent in effect (to): his statement was tantamount to an admission of guilt
Word Origin
C17: basically from Anglo-French tant amunter to amount to as much, from tant so much + amunter to amount
Word Origin and History for tantamount
adj.
1640s, from verbal phrase tant amount "be equivalent" (1620s), from Anglo-French tant amunter "amount to as much" (late 13c.), from Old French tant "as much" (from Latin tantus, from tam "so") + amonter "amount to, go up" (see amount).