Richard Nixon had ‘My fellow Americans.’ George W. Bush has ‘Folks.’ Increasingly, Barack Obama is revealing the latest linguistic fingerprint of leadership: ‘Look.’

In Monday’s press conference to announce his national security team, Obama slipped in at least two ‘looks’ — a colloquialism in which the president-elect regularly indulges. Anyone who listened closely to Obama’s sentences during the primaries and general election would not have been surprised. By now, ‘Look’ is a certified Obamaism, as fundamental a signature of the next president’s lexicon as ‘Friends, Romans, countrymen’ was to that of Mark Antony.

Asked by a reporter how he could justify appointing Sen. Hillary Clinton to the job of secretary of state, after denigrating her foreign policy credentials when both were vying for the Democratic presidential nomination not too long ago, Obama replied, ‘Look — I think this is fun for the press, to try to stir up whatever quotes were generated during the course of the campaign … and you’re having fun. And there’s nothing wrong with that.’

When the reporter persisted with his point, the president-elect said, ‘But look — I think if you look at the statements that Hillary Clinton and I have made outside of the heat of a campaign, we share a view that America has to be kept safe and secure.’

The word ‘look’ often introduces what grammarians call an imperative sentence. ‘Imperative’ comes from the Latin word for ‘command’ — a fitting etymology for a word beloved by a newly minted commander in chief.

Obama’s affection for ‘look’ — which he sometimes swaps out for ‘Understand’ — may date to his days as an instructor at the University of Chicago law school. The word does have a certain professorial — and, some might say, condescending and even belittling — ring to it. The implication: ‘Look, buddy, here’s why you’re all wet.’

In the days ahead, keep an ear cocked for ‘look’ at the outset of the new president’s sentences. Perhaps a drinking game may emerge: Take a swig each time Obama says the word — although given the shaky state of the economy he is inheriting, the beverage of choice for the ‘Look’ game may be water.