I did quite a bit of rooting around amongst the various definitions and I definitely think you're using it wrong. The wikipedia definition is, IMO, not incorrect, but incomplete. It focuses on trading the player for draft picks and prospects w/o mentioning that there's a "below market value" aspect.
You're relying on "I would have traded for picks + young guys" = firesale. If that's all that's required, then if I traded Manning for 3 first round picks, I'd be having a fire sale, right? No, because I'm not letting him go for less than market value.
The whole point of the firesale is that you're letting high value guys go for significantly less than market value.
You wanted Gore + a 1st rounder for Steve Smith? That's not even remotely a firesale. If that happened, it'd just be a trade: value for value (and of course arguable how equivalent, but it's clearly value on each side).
Give up Steve Smith for a 2nd rounder because you're out of it and it's the best offer on the table, even though you know he's worth more? That's a firesale.
Better example: I actually did trade Steve Smith for a 2nd rounder + S. Holmes (young prospect) + T. Jackson (young prospect). Firesale? By your definition, yes. But I didn't sell him for less than market value (in my mind at the time), so it was just a value for value trade: present value for future value.
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Some selected info I relied on:
Oxford dictionary: "a sale of goods or assets at a very low price"
Merriam Webster dictionary: "a sale at very low prices"
Current Sacramento Bee article regarding the Kings trying to trade Ron Artest (
http://www.sacbee.com/100/story/177884.html):
"With teams afraid of the forward, the Kings might have to dump him for little in return."
"There is a likelihood that the Kings will have to swallow hard and take a fire-sale deal to move Artest."