An uneasy or distressing desire (for something).
An unpleasant state of mental uneasiness, nervousness, apprehension and obsession or concern about some uncertain event.
A state of restlessness and agitation, often accompanied by a distressing sense of oppression or tightness in the stomach.
Something that perplexes.
The state or quality of being perplexed; puzzled or confused.
In information theory, a measurement of how well a probability distribution or model predicts a sample.