Definition

No so much a definition, but when a writer uss that term, it generally means here is a specialized tax term.

So in tax parlance, a 'wash sale' means you sold securities and within +/- 30 days you purchased substantially identical securities.

Now you are left to find the specialized meanings of securities, substantially identical, sold and purchased.

I don't usually teach English or Grammar, but I'll give it a try.

First, you have TWO words here and to ask for a definition you need to ask for it based each word individually.

I'll ignore the definition of word "tax" since that seems to NOT be the issue. But I'd like to note that in this case, TAX is a qualifier or modifier, meaning it qualifies or modifies the meaning of the word parlance to tax issues.

The word "parlance" means "a way or manner of speaking; vernacular; idiom". For example, Tax Parlance generally MEANS speaking in terms or words that are specific to the qualifier tax. For example "In bureaucratic parlance, your proposal would be described as cost effective. In football parlance, it's a touch down."

Specific to tax situations, parlance would be used to describe how one spoke about a tax topic - In tax parlance, your deduction does not rise to the level of a sustainable deduction under IRC 162. In common parlance, you lose the tax deduction!"

Hope this helps, Gene E. Utterback, EA, RFC, ABA