What does Butterfly keyboard mean?

Butterfly keyboard meaning in Computer Science Dictionary

Keyboard first introduced regarding the IBM ThinkPad 701 in 1995 that permitted for a bigger keyboard (11.5 ins) with an inferior scaled-down laptop. The image shows a butterfly keyboard that expands once the laptop computer lid is exposed. While the laptop closes the keyboard collapses once again. Considering poor product sales and bigger laptop computers with bigger shows this keyboard was just on the IBM ThinkPad 701 and contains not been combined with any kind of laptops.