1 contestably, controversially, controvertibly, debatably, deniably, disputably, dubitably, questionably, refutably
2 conceivably, feasibly, plausibly, possibly, potentially
English Collins Dictionary - English synonyms & Thesaurus
You can use arguably when you are stating your opinion or belief, as a way of giving more authority to it. adv ADV with cl/group, ADV before v
They are arguably the most important band since The Rolling Stones...
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