Without compunction; lacking guilt, regret, or hesitation; shameless.
From 'compunction' + suffix '-less' (without). The suffix '-less' has been productive in English for over a thousand years, allowing speakers to create opposite meanings by negation.
The phrase 'without compunction' appears constantly in crime reporting and psychology because psychopaths literally show reduced activation in brain regions that process guilt—they're neurologically accurate to the word's literal meaning.
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