Australian term for what the rest of the world calls a duvet or an eiderdown, and Americans call a comforter.
Usually made from two large pieces of tight weave cotton stitched together to form a large, flat 'pillow' stuffed (traditionally) with down, or in cheaper versions, with nylon filler. There are usually lines of stitching down the middle to stop the filler moving around, but this doesn't always work, and a common problem in older doonas is to have toasty warm feet and a freezing upper body. This is easily remedied by giving the thing a good shake. The doona is usually covered in a 'pillowcase' type cover with buttons, snaps, or a zip at the bottom.
Unlike most blankets, the doona is often used without a top sheet, as the doona cover protects the doona in the way a sheet would normally protect a blanket. This means that you need to wash and/or change your doona cover as often as you change your sheets, but because the tendency is to think of it as a 'blanket' it's easy to go for far too long without remembering to do it.
Doonas are perfect for bringing with you to your computer chair or couch for game playing or movie watching, mostly because their 'puffy' shape lends itself to filling in all the little gaps around your body that let the cold air in with normal blankets.
One of the other beautiful things about the doona is that it takes a long time to lose the warmth it absorbs from your body, so if you get up in the night and then go back to bed later on, your bed will still be just as warm as when you got up. The value of this must not be underestimated.
You know what I'm talking about.
Sharq provided me with a piece of VERY interesting info: in Norwegian, a duvet is called a "Dyne". Pronounced "Duu-Neh". Which is pretty close to doona indeed. Anyone else with info on the etymology of this word, a /msg would be appreciated!
AnotherMartini tells me that he's
'pretty sure that the reason why 'doona' is an Australianism is that it was originally an Australian brand of duvet, and the brand name has drifted into generic use like Dictaphone, Band-Aid or Bean Bag. Sharq is probably on to something with the etymology of the brand name though.'
Which sounds right to me. Further investigation proves that the doona I have at home is actually a 'Doona' (capitalisation intended). There you have it.
A little more research by 'Martini has revealed that the Doona brand is currently owned by Pacific Brands, who used to be part of Pacific Dunlop. Pacific Brands also own all those aussie brands like Bonds and Dunlop.
Gritchka would like to add that an eiderdown or a quilt goes on top of blankets (because it's real cold out), but a doona or duvet is instead of them.
G would also like to point out that an eiderdown or quilt is stitched to stop the guts of it moving around, but that a doona or duvet is designed to be adjustable. Wild. | 
