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A very large or drastic reorganization of the management or administration within a company, agency, department, etc., especially resulting in the dismissal of people from their posts or employment. Sometimes hyphenated. Many feared that the shake-up would result in the department no longer being as effective as it once had been. This company needs a major shakeup if it is going to stay afloat in today's economy.
n. a reorganization. After a shake-up like the one we’ve just been through, everybody’s a little upset.