late 14c., fixacion, an alchemical word, "action of reducing a volatile substance to a permanent bodily form," from Medieval Latin fixationem (nominative fixatio), noun of action from past participle stem of Latin fixare, frequentative of figere "to fix" (see fix (v.)). Meaning "condition of being fixed" is from 1630s. Used in the Freudian sense since 1910.
