Trauma (n.) is a condition constituted in two non-traumatic events... first, the early event (which was not intrinsically traumatic because one was too young to process it) and a second event (which also was not traumatic) but triggered the memory which was retrospectively given a traumatic meaning.
Trauma (n.) is a wound or breach in the mind's experience of time... a traumatic event is experienced too early (or too soon) to be fully known or understood and therefore is unavailable to consciousness.
Trauma (n.) is an economic concept and refers to a massive cathexis of external stimulus that breaches the protective shield of the perceptual-consciousness system or ego. Trauma is shock and complete surprise.
Trauma (n.) is an excess of excitation that disrupts psychical equilibrium and is consequently experienced as unpleasurable.
Trauma (n.) is both a specific event (a railway accident) and the symptomatic responses that later emerge.
Trauma (n.) is never contained in a single moment. The traumatic 'event' is defined by a temporal structure.
Trauma (n.) is not the event itself. It is the way that its very unassimilated nature (the way it was precisely not known in the first instance) returns to haunt the survivor later on.
Trauma (n.) is situated in the framework of the death drive.