Anxiety

n. fear, worry; eagerness

Anxiety is a physiological state characterized by cognitive, somatic, emotional, and behavioral components (Seligman, Walker & Rosenhan, 2001). These components combine to create the feelings that we typically recognize as fear, apprehension, or worry. Anxiety is often accompanied by physical sensations such as heart palpitations, nausea, chest pain, shortness of breath, or headache.
See more at Wikipedia.org...

Anxiety is a multisystem response to a perceived threat or danger. It reflects a combination of biochemical changes in the body, [more]Anxiety - Community and Resources

Noun
1. a relatively permanent state of anxiety occurring in a variety of mental disorders
(synonym) anxiousness
(hypernym) psychological state, mental state
(hyponym) castration anxiety
2. a vague unpleasant emotion that is experienced in anticipation of some (usually ill-defined) misfortune
(hypernym) emotion
(hyponym) discomfiture, discomposure, disconcertion, disconcertment

(n.)
Eager desire.
  

(n.)
Concern or solicitude respecting some thing or event, future or uncertain, which disturbs the mind, and keeps it in a state of painful uneasiness.
  

(n.)
A state of restlessness and agitation, often with general indisposition and a distressing sense of oppression at the epigastrium.