Examples from the Web for thoughtlessness
Unless said partner is ready to be whacked over their head with the box for their thoughtlessness, they have made a grave mistake.
Thoughtlessness regarding his neighbours is not a poor man's vice.The Expositor's Bible: The Second Book of Samuel|W. G. Blaikie
While terrified leaders passed from arrogance or thoughtlessness to dejection and confusion, the blow was being struck.Battle Studies|Charles-Jean-Jacques-Joseph Ardant du Picq
Then having thus spoken, they lay down out of the pathway among the dead; but he, in thoughtlessness, ran hastily past.
A moment's thoughtlessness on the part of An-ina, on the part of his Indians, and the mischief would be done.The Heart of Unaga|Ridgwell Cullum
And yet his crime was committed more in thoughtlessness than deliberate depravity.A Connecticut Yankee in King Arthur's Court, Complete|Mark Twain (Samuel Clemens)