This is the 942nd most frequent Greek word.
εντελώς
Completely; entirely.
Here, 'εντελώς' is used as an adverb meaning 'completely' to emphasize the total emptiness.
Το σπίτι είναι εντελώς άδειο.
The house is completely empty.
Here, 'εντελώς' modifies the adjective 'παράλογη' (absurd) to express the extreme level of absurdity.
Αυτή η ιδέα είναι εντελώς παράλογη.
This idea is utterly absurd.
In this context, 'εντελώς' is used to reinforce the certainty expressed by the adjective 'σίγουρος' (sure).