All momentously synonyms

adverb momentously

• crucially — involving an extremely important decision or result; decisive; critical: a crucial experiment.
• importantly — of much or great significance or consequence: an important event in world history.
• gravely — Samuel L(ee), Jr. 1922–2004, U.S. naval officer: first black admiral.
• significantly — important; of consequence.
• critically — inclined to find fault or to judge with severity, often too readily.
• remarkably — notably or conspicuously unusual; extraordinary: a remarkable change.
• extremely — To a very great degree ; very.
• seriously — in a serious manner: He shook his head seriously.
• hugely — extraordinarily large in bulk, quantity, or extent: a huge ship; a huge portion of ice cream.
• fatefully — having momentous significance or consequences; decisively important; portentous: a fateful meeting between the leaders of the two countries.
• decisively — having the power or quality of deciding; putting an end to controversy; crucial or most important: Your argument was the decisive one.