Philosophy absolutely has the ability to examine and propose better definitions when definitions (like the ones you linked) do not capture the phenomenon. Losurdo read more books than you’ve seen by liberals in order to write his “Liberalism” book. He understood the phenomenon deeper and further than its dictionary use.
How do you capture such a thing in your world view? Because he found flaws in definitions and worked deeper, he just did nothing because it wasnt the Oxford definition?