From the Merriam-Webster dictionary:

Full Definition of lame duck

1: one that is weak or that falls behind in ability or achievement; especially chiefly British : an ailing company

2: an elected official or group continuing to hold political office during the period between the election and the inauguration of a successor

3: one whose position or term of office will soon end

The customary and most-frequent usage of the term in the United States is the second: to describe that odd interregnum between the new officeholder’s election and his or her installation in the office.

The Republicans in the US Senate prefer the less-used third definition to explain why they won’t even hold hearings to consider anyone President Obama might nominate to replace Justice Scalia on the Supreme Court bench. It seems to me that it’s unconstitutional not to hold a hearing; the Senate is supposed to advise and consent (or not), not to run out the clock. And this is instructive: Majority Leader Senator McConnell says he might not even give a floor vote to the next nominee after the election. I can predict that if the Republican candidate for President wins he’ll be happy to have hearings and a vote.

They really are despicable. The country deserves better than this.