See fluster in Webster's New World Roget's A-Z Thesaurus II
verb
To impair or destroy the composure of:
agitate, bother, discompose, disquiet, distract, disturb, flurry, perturb, rock, ruffle, shake (up), toss, unsettle, upset. (Informal) rattle. See calm
noun
A state of discomposure:
agitation, dither, flutter, perturbation, tumult, turmoil, upset. (Informal) lather, stew. See calm
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