An attachable keyboard refers to a keyboard that can be connected or attached to another device, such as a tablet or a smartphone, to provide the user with a physical keyboard for typing. Full definition
The keys are very comfortable to type on, and it doesn't feel shaky like you might find with attachable keyboards from other PC manufacturers. (neowin.net)
Optional attachable keyboard with extra battery for laptop form - factor. (umpcportal.com)
Likened to Microsoft's Surface Pro, the Galaxy Book 12 (about $ 1,150) has an included attachable keyboard and S Pen for inking, but it makes a fine tablet on its own with its 1440p display. (windowscentral.com)