An unpleasant state of mental uneasiness, nervousness, apprehension and obsession or concern about some uncertain event.
An uneasy or distressing desire (for something).
A state of restlessness and agitation, often accompanied by a distressing sense of oppression or tightness in the stomach.
A complete obsession or absorption in a subject or hobby to a point where a person appears to completely tune out their surroundings and where the person repeatedly returns to said subject or material.