An expense; typically an unusual expense, as opposed to an ongoing and predictable cost of doing business.
Management often uses adjectives like "non-recurring" and "cashless" to imply that a charge is harmless and that investors shouldn't worry about it.
Here's an example: suppose a retailer has some inventory that hasn't moved in years.
This stuff is still carried on the balance sheet as an asset, but its real market value is basically zero because no one wants it.
Suppose that management decides to stop paying to store this stuff, and to just throw it out instead.
Dropping this asset would throw the balance sheet out of balance; so they write a charge on the income statement, which flows through to the bottom of the balance sheet because it causes retained earnings to decrease.
Now everything is in balance and accounted for.
If you were to glance at the annual report, the effect of this maneuver would look terrible:
you'd see that assets and earnings both took a hit, and you'd freak out.
So management would make sure to emphasize that this was due to a special, non-recurring, cashless, on-paper charge, and you'd probably stop worrying.
But even though the liquidation itself was probably a smart move, the whole story is not really completely "harmless".
Shareholders' equity really was spent at one time to acquire that stuff, with the expectation that it would bring in revenue;
but management let them down, and wasted it.
So whenever you see the word "charge", you should suspect that it represents a real payout of money, and not be too quick to "write it off".