wash sale n[probably from the comparison of such a sale to the act of washing, which does not affect the nature of the thing washed]
: a sale and purchase of securities that produces no change of the beneficial owner
: a sale of securities within 30 days before or after the purchase of substantially identical securities NOTE: Any loss from such a sale is not deductible for most taxpayers under the Internal Revenue Code.
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.