Works the same as M-b for me (backwards-word)

Make sure your /etc/inputrc or ~/.inputrc contains

# mappings for Ctrl-left-arrow and Ctrl-right-arrow for word moving

"\e[1;5C": forward-word

"\e[1;5D": backward-word

"\e[5C": forward-word

"\e[5D": backward-word

"\e\e[C": forward-word

"\e\e[D": backward-word`