This is the 4452nd most frequent Russian word.
возможным
Possible.
Here, 'возможным' is used as an adjective in instrumental case to describe the consideration's nature.
Считаю это вполне возможным.
I consider this quite possible.
In this sentence, 'возможным' functions as a predicate adjective describing the extent of what was done.
Он пытался сделать всё возможным.
He tried to do everything possible.
Here, 'возможным' serves as an adjective in instrumental case as part of the predicate to denote feasibility.