Formidably

['fɔ:midəbli]

(adv.) in a formidable manner; 'the constant risk that attends the exchanges of human beings formidably armed'.

Edited by Aaron--From WordNet

(adv.) In a formidable manner.

Checker: Lyman

Their bayonets and spearheads glistened in the sunlight formidably. Ulysses S. Grant. Personal Memoirs of U. S. Grant.

Checker: Lyman