An interference with the occurrence of an instigated goal-response at its proper time in the behavior sequence. Frustrations are aversive events and generate aggressive inclinations only to the extent that they produce negative affect.
Dollard, J., Miller, N. E., Doob, L. W., Mowrer, O. H., & Sears, R. R. (1939). Frustration and aggression. New Haven: Yale University Press. doi: 10.1037/10022-000; Berkowitz, L. (1989). Frustration-aggression hypothesis: examination and reformulation. Psychological Bulletin, 106(1), 59-73. doi: 10.1037/0033-2909.106.1.59