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Huawei unveils world’s first tri-fold phone, the Mate XT Ultimate Design
(spillsomebeans.com)
This is a most excellent place for technology news and articles.
Pedantic return: it has 3 screens with 2 connecting hinges, it is therefore trifold.
trifold in American English (ˈtraiˌfould) adjective
And two fold is how many screens ?
2, with 1 hinge. It's like a normal phone but the screen number increased twofold.
Bifold means something that folds into two parts. Consider the bifold wallet or bifold door.
How can something fold into one part then ?
I guess the same way you slice something into one piece. Bisect is one less than trisect, so what's one less than bisect?
Maybe the problem is that the phone is rectangular. I bet they could do it with a polygon with just two fewer sides. ;)