Anxiety (n.) is a reaction to a situation of danger that is both mental [apprehension, worry, etc.] and bodily [breathlessness, palpitations, muscle tension, fatigue, dizziness, sweating and tremor, etc.].
Anxiety (n.) is an experience of helplessness in the face of an accumulation of excitation that cannot be discharged.
Anxiety (n.) is, in children, originally nothing other than an expression of the fact they are feeling the loss of the person they love.
Anxiety (n.) is nothing other than a repressed affect.
Anxiety (n.) is rooted in man's biological nature and can be explained in terms of natural cause and effect processes.
Anxiety (n.) is simply a transformation of sexual libido that has not been adequately discharged.
Anxiety (n.) arises in the face of situations of danger.
Anxiety's (n.) first experience, source, and prototype is birth.