NEW YORK (AP) _ C R - - - - - - D.

Depending on your outlook, it's a nine-letter word for either frustration or fun. The crossword puzzle, which turned 75 today, thrives because of those elements, experts say.

It can be frustrating, for instance, to ponder what four-letter word matches the clue ''wedding-cake artisan,'' but fun to find that ''icer'' fits perfectly.

''Most of the problems we have in everyday life don't have clear-cut solutions,'' said Will Shortz, editor of Games magazine. ''Crossword puzzles have definitive answers, and when you get that answer, it's a very satisfying feeling.''

Surveys show that 27 million people across - and down - the country do crosswords regularly, and more than twice that many do them occasionally.

Crosswords are descended from the ancient word square game; elementary forms appeared in children's books in England during the 19th century. But the modern crossword was invented, out of necessity, by Arthur Wynne, editor of the ''Fun'' supplement of the New York World.

''It was the Sunday before Christmas, and he had a page to fill,'' Shortz said. The diamond-shaped, 31-clue ''Word-Cross'' puzzle ran on Dec. 21, 1913, and was an immediate hit.

A typesetter transposed the words four weeks later, and the name crossword stuck. A crossword cult formed among readers of the World, other papers began running puzzles, and by 1924, it was a full-fledged craze.

The black-and-white crossword design showed up in jewelry and on dresses; trains carried dictionaries and printed crosswords on the backs of menus; the New York Graphic magazine ran a contest with $25,000 in prize money.

Simon & Schuster's first publication was a book of crossword puzzles that sold half a million copies in a single year.

More and more newspapers printed puzzles, with the notable exception of The New York Times, which dismissed them as ''a primitive sort of mental exercise'' that would soon fade.

The craze faded, but the puzzles persisted. By 1942, even the Times had relented, hiring Simon & Schuster editor Margaret Petherbridge Farrar to edit its crossword puzzle. The influential ''grand lady of crosswords,'' as Shortz calls her, stayed in that position until 1969.

Mrs. Farrar helped bring themes, humor and ''modern playfulness'' to crosswords, Shortz said. Currently, a new school of puzzle makers favors even more puns, jokes, fresh definitions or clues, pop culture references and the living language, or non-dictionary phrases, Shortz said.

Virtually all of the puzzles printed today are written by about 200 writers, or ''constructors,'' according to Shortz, with another 1,000 or 2,000 people doing it occasionally.

''It takes a lot of patience,'' said Maura Jacobson, who got her start under Mrs. Farrar's tutelage and now creates puzzles for New York magazine.

Mrs. Jacobson, a former kindergarten teacher, one-time ''Jeopardy 3/8'' contestant and ''trivia nut,'' said it takes her about 25 hours to write a typical puzzle, somewhat longer than other constructors, she said.

Mrs. Jacobson starts with her theme, then lists theme-related words, two of each length - a true crossword is symmetrical. Then she crosses the theme words, puts a black square where they end and fills in the rest.

''Sometimes you get to the point where you have a great corner, everything crossing nicely, and you find there's no such word,'' said Mrs. Jacobson, who lives in Hartsdale. ''Then you have to start over.

''I go through more erasers than pencils,'' she said with a laugh.

Her 25 hours of work can be polished off in mere minutes by a world-class solver like Doug Hoylman, 45, an actuary from Chevy Chase, Md., who won the American Crossword Puzzle Tournament in August. He does the Washington Post daily puzzle in about five minutes. The New York Times' puzzle takes maybe 10.

''I prefer to use pencils,'' he said. ''I make mistakes like everyone else, and I have no need to impress anybody.''

Good solvers, Hoylman said, have a broad range of knowledge and, of course, are good with words.

''It takes the kind of mind more oriented to print than speech - someone who thinks of a word as a group of letters rather than a sound,'' he said.

Rebecca Kornbluh, a 38-year-old weaver who lives in Mundelein, Ill., won the U.S. Open crossword championship for three straight years, but has retired from competition. The Brooklyn native still buys The New York Times on Sunday, however.

''There's not too much of a challenge anymore,'' she said. ''It's only how fast you can do it, and that's a way to miss the fun and subtlety of modern- day crosswords - the puns, the wordplay, the off-the-wall definitions.''

According to these experts, the most challenging puzzles can be found in Games magazine, the Dell ''Champion'' series, and the Sunday puzzles of Newsday, the San Francisco Examiner, The Boston Globe, The Washington Post and The New York Times.

''Crosswords are popular because of the appeal of playing with words, the humor in the clues and themes, and because of the aesthetic appeal of the black and white squares,'' Shortz said. ''There's something very attractive about those empty squares - they just beg to be filled in.''