What is "sheerly"

Usage examples of "sheerly".

Unless he had gone sheerly cuckoo, he couldn't hope to steal so much as a spoon that night, after his intentions had been so widely and openly proclaimed, without convicting himself on his own confession.

Now it has become to such an extent a sheerly mechanistic world, as interpreted through our physical sciences, Marxist sociology, and behavioristic psychology, that we're nothing but a predictable pattern of wires responding to stimuli.

He was operating sheerly on instinct, a soldier ant mindlessly constructing fortifications.