ominous + -ly
ominously (comparative more ominously, superlative most ominously)
- in an ominous manner; with sinister foreboding.
1868, Wilkie Collins, The Moonstone:
From first to last he was ominously polite, and ominously silent.
1983, Patricia Hagan, Golden Roses:
His nostrils flared ominously and his fists opened and closed at his sides.
1999, Harish Kapadia, “Accident and Rescue in the Nanda Devi Sanctuary”, in Across Peaks & Passes in Kumaun Himalaya, New Delhi: Indus Publishing Company, →ISBN, page 70:
However, the next day dawned ominously with an overcast sky and we postponed our start till 8 o'clock.