Semantics is the Big Washington Game, but no one is quibbling over this: 257 works of art owned by John Q. Public are among the missing.

Missing, in the view of the National Collection of Fine Arts, is not the right word. Nor is "unlocated." Nor is "purloined," or any word like that.

Semantics aside, it is believed the art works are somewhere in the White House, in the old Executive Office Building next door, across the street at Blair House or out in the Maryland country-side at Camp David.

But no one knows for certain, and that is the problem.

The problem was brought to light by The National Journal, a governmental affairs weekly, which raised the possibility that at least some of NCFA's art works may have their way into private collections of former White House employes.

And some in the present administration have even gone so far as to imply the same thing - that the paintings went the way of their admirers - out.

The absence of the 257 works of art, mostly paintings, was discovered when officials of the NCFA began a review of loans made to presidential staffers since 1929.

According to the NCFA, 1,930 pieces of art have gone on loan to the White House and environs.All but the 257 are accounted for.

NCFA rejects the idea that they are lost, infindable or any other euphemistic synonym. But it is not certain.

"The word 'unlocated' implies that I or someone went over and conducted a thorough search.We have not done that, and until we have, I think 'outstanding' is a better word," said Robert johnston, the NCFA registrat.

"Until we had a chance to go and look, we can't say they are missing. It will take a long time and a lot of prying into closets," he said.

Does NCFA intend to make a formal requests to gain access to those security-tight hallways of the executive complex?

"I don't see how we can avoid making a formal requests," Johnston said.

Joshua Taylor, director of the NCFA, described the situation in another way. He said the list of 257 was an "innocent" inventory of works "that we are checking physically to determine present location and to re-lend or recall to the museum."

About the possibility of outright theft, he said: "We are resigned to the fact that some few . . . may have become so important to their borrowers that they went with them into retirement."

The inventory of the 257 indicates that many of the works were intended for other than White House staff viewing. Among the borrowers were the CIA, the old Office of Economic Opportunity, the Council of Economic Advisers and someone called "White House helicopters."STAmong other borrowers named on the list are former presidents Truman and Nixon, and former vice president Spiro T. Agnew and Nelson A. Rockefeller.

Johnston said that in those cases the NCFA records indicate the names of staff assistants to whom the paintings were loaned and that they could possibly be traced that way.

Johnston, NCFA Assistant Director Harry Lowe and others at the museum, a branch of the Smithsonian Institution, contended that part of their problem is that Clement Conger, the White House art curator, isn't being very co-operative.

They said NCFA has asked Conger for help in tracking down the art, but the help has not been forthcoming. "The curator will take no responsibility to help us," Lowe said.

Conger is out of the country, on vacation, but Betty Monkman, registrar in his office, said assistance has been promised in looking for paintings - in the White House.

"We've said we can't control things in the EOB, and we can't take responsibility for the art works there," she said.

The National Journal reported that, near the end of the Nixon administration when NCFA became concerned that loaned objects were being neglected, it found pictures assigned to Nixon's helicopter were in fact in housing quarters for U.S. fliers.

Johnston said that since early 1977 a tighter loan and regitration policy has been in effect at the museum. Any painting loaned to the White House or its adjuncts since then has been signed for by its individual borrower.

NCFA says it is unable to place a value on the "outstanding" paintings. But then, who knows what's missing?