successful

be, prove, seem

become

astonishingly, enormously, extremely, highly, hugely, outstandingly, particularly, phenomenally, remarkably, spectacularly, very

The startup's hugely successful app attracted millions of users within just six months.

not entirely

The new restaurant was not entirely successful, so they made changes to the menu.

fairly, moderately, partially, quite, rather, relatively

My first business attempt was relatively successful, though I made several mistakes along the way.

academically, commercially, politically

The new smartphone was commercially successful, selling millions of units worldwide.

at

She has always been successful at finding creative solutions to difficult problems.

in

The new restaurant has been very successful in attracting customers from the neighborhood.