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Define name

Windows shortcut 
CtrlF3
Mac shortcut 
FnF3

In Windows, this shortcut now displays the Name Manager dialog, where you can click the New button, to create a new name. There is no actual shortcut for to create a single new name, except through the ribbon: Alt M + MD

On a Mac, this shortcut displays the Define Name dialog box, which offers to name a range based on the current selection.