One can move forwards / backwards one word using Ctrl+Space and Meta+Space respectively.
How can I bind META+Left arrow to move backwards one word / META+Right to move forwards one word?
Thx for helping.
According to the manual page for nanorc, you cannot do this. It does not accept bindings for special keys modified by meta. This is what it says regarding M- (the meta-modifier):
M-followed by a printable character or the word "Space". Example: M-C
A similar question was asked in Bind Ctrl+Right to nextword in nano (as it is in all other apps)