apprehensiveness

strain, stress, tension

alarm (also alarum), anguish, consternation, desperateness, desperation, discomfort, discomposure, dismay, distraction, distress, disturbance, edginess, franticness, hand-wringing, jitters, jumpiness, panic, tremor

angst, fearfulness, torment, upset, vexation

cold feet, doubt, dread, foreboding, incertitude, misgiving, presentiment, suspense, uncertainty

compunction, qualm, scruple

agitation, anxiety, anxiousness, concern, disquiet, disquietude, distress, disturbance, fearfulness, funk, perturbation, solicitude, suspense, unease, uneasiness

scruple, worry

doubt, incertitude, mistrust, suspiciousness, uncertainty, wariness

defeatism, pessimism

foreknowledge, premonition, presage, presentiment