ar ‧ gu ‧ a ‧ bly /ˈɑːɡjuəbli $ ˈɑːr-/ BrE AmE adverb [sentence adverb]
[ Word Family: adjective : ↑ arguable , ↑ argumentative ; verb : ↑ argue ; noun : ↑ argument ; adverb : ↑ arguably ]
used when giving your opinion to say that there are good reasons why something might be true:
Senna was arguably the greatest racing driver of all time.