Definition of "aroar"

[…] scarcely five minutes had passed since Captain Ransome’s guns had broken the truce of doubt before the whole region was aroar: the enemy had attacked nearly everywhere.

1893, Ambrose Bierce, “One Kind of Officer”, in Tales of Soldiers and Civilians, and Other Stories‎, page 90

The great room, ordinarily aroar with life, was still and gloomy as a tomb.

1903, Jack London, “Too Much Gold”, in The Faith of Men, and Other Stories‎, New York: Macmillan, page 105

A ground swell set in; the beach was aroar with incoming waves;

1956, Yukio Mishima, chapter 8, in Meredith Weatherby, transl., The Sound of Waves‎, Tokyo: Charles E. Tuttle, page 64