Real Dictionary

wash sale in British English
the pretended trading of stock, accomplished by buying shares at one broker and simultaneously selling an equal number of shares at another broker, in order to make trade in that stock appear active: an illegal practice
noun: a sale of a stock at a loss and repurchase of the same or substantially identical stock within 30 days, for which the capital loss is disallowed for tax purposes
noun: the illegal stock-exchange practice of buying and selling the same securities at an inflated price through a colluding broker to give the impression that the security has a strong market

wash sale in Finance
noun: A wash sale is the act of selling a security at a loss and then buying the same security again shortly after.