Plain English Meaning
Your mind quietly buries something stressful before you even realize you're doing it, so you don't feel the discomfort but the issue is still there underneath.
Full Definition
A defense mechanism in which a person pushes uncomfortable thoughts, memories, or feelings out of awareness without deliberate intent, so that the suppression itself is not consciously chosen or noticed.
Context Anchor
Seen in the Aviation Instructor’s Handbook discussion of human behavior, especially when explaining why a learner may resist, deny, or avoid something during training.
Derivation
From Latin 'conscius' (aware, knowing) with the prefix 'un-' (not), combined with 'effort' (a deliberate action). Literally an action taken without awareness of taking it -- which captures the key idea that the person isn't choosing to push the thought away, it just happens.
Why Pilots Care
Reduces during , allowing more for and .