Στο "Annales Médico-psychologiques, revue psychiatrique" (Volume 164 Issue 2, March 2006, Pages 99-107), αναφέρεται ότι:
"... Appearing in the 13th century with the general meaning of “an action to refuse something to somebody”, the obligatory). After the 17th century, it means to deny a fact. In modern language, it is used in a more restricted sense and mainly in legal expressions. “Dénégation” from the Latin “denegatio” is a late 14th century loan of a legal expression that means rejection. In the first place, it describes a situation when a person maintains that a fact reported by another one is not true. At the end of the 18th century, it is the refusal to recognise a fact. Nowadays, the expression is defined by the fact of negation or denial. In French literature, denegation is used more frequently than denial.In psychiatry, denial represents a reactive, defensive and unconscious mechanism used by a subject confronted with an invasion of anxiety as a reaction to trauma or disease. It is present in certain paradoxical situations where a normal personality is overtaxed by a major traumatic event that generates cracks and discontinuities in the tissue of this psychic reality..."
Οι 10 βασικοί μηχανισμοί άμυνας του Εγώ, σύμφωνα με τον Freud, είναι: Άρνηση, απώθηση, παλινδρόμηση, διάσχιση, προβολή, αντισταθμιστική συμπτωματολογία, μετάθεση, διανοητικοποίηση, εκλογίκευση, μετουσίωση. Σε ορισμένους εξ αυτών αντιστοιχούν και περισσότεροι όροι.