The prefix "ent" in German often signifies a taking-away or removal; I thus find it somewhat amusing that Enttäuschung means "disappointment". The Täuschungen whisked away are: deceptions.
Oddly, one of the definitions of "decipere" in my ancient miniature Latin dictionary is "disappoint". Lewis & Short write of one use of it
Of inanimate objects: exspectationibus decipiendis, so.