Among the facts in the new edition of Ethnologue, a sprawling compendium of
the world's languages, are that 119 of them are sign languages for the deaf and
that 497 are nearly extinct. Only one artificial language has native speakers.
(Yes, it's Esperanto.) Most languages have fewer than a million speakers, and
the most linguistically diverse nation on the planet is Papua New Guinea. The
least diverse? Haiti.

Opening the 1,200-page book at random, one can read about Garo, spoken by
102,000 people in Bangladesh and 575,000 in India, which is written with the
Roman alphabet, or about Bernde, spoken by 2,000 people in Chad. Ethnologue,
which began as a 40-language guide for Christian missionaries in 1951, has grown
so comprehensive it is a source for academics and governments, and the
occasional game show.

Though its unusual history draws some criticism among secular linguists, the
Ethnologue is also praised for its breadth. ''If I'm teaching field methods and
a student says I'm a speaker of X, I go look it up in Ethnologue,'' said Tony
Woodbury, linguistics chairman at the University of Texas. ''To locate a
language geographically, to locate it in the language family it belongs to,
Ethnologue is the one-stop place to look.''

Yet Ethnologue's most curious fact highlights a quandary that has long
perplexed linguists: how many languages are spoken on the planet?

Estimates have ranged from 3,000 to 10,000, but Ethnologue confidently
counts 6,912 languages. Curiously, this edition adds 103 languages to the 6,809
that were listed in its 2000 edition -- at a time when linguists are making dire
predictions that hundreds of languages will soon become extinct.

''I occasionally note in my comments to the press,'' said Nicholas Ostler,
the president of the Foundation for Endangered Languages, ''the irony that
Ethnologue's total count of known languages keeps going up with each four-yearly
edition, even as we solemnly intone the factoid that a language dies out every
two weeks.''

This dissonance points to a more basic problem. ''There's no actual number
of languages,'' said Merritt Ruhlen, a linguist at Stanford whose own count is '
'around'' 4,580. ''It kind of depends on how one defines dialects and languages.
''

The linguists behind the Ethnologue agree that the distinctions can be
indistinct. ''We tend to see languages as basically marbles, and we're trying to
get all the marbles in our bag and count how many marbles we have,'' said M.
Paul Lewis, a linguist who manages the Ethnologue database (www.ethnologue.com)
and will edit the 16th edition. ''Language is a lot more like oatmeal, where
there are some clearly defined units but it's very fuzzy around the edges.''

The Yiddish linguist Max Weinrich once famously said, ''A shprakh iz a
diyalekt mit an armey un a flot'' (or ''a language is a dialect with an army and
a navy''). To Ethnologue, and to the language research organization that
produces it, S.I.L. International, a language is a dialect that needs its
literature, including a Bible.

Based in Dallas, S.I.L. (which stands for Summer Institute of Linguistics)
trains missionaries to be linguists, sending them to learn local languages,
design alphabets for unwritten languages and introduce literacy. Before they
begin translating the Bible, they find out how many translations are needed by
testing the degree to which speech varieties are mutually unintelligible. ''The
definition of language we use in the Ethnologue places a strong emphasis,'' said
Dr. Lewis, ''on the ability to intercommunicate as the test for splitting or
joining.''

Thus, the fewer words from Dialect B that a speaker of Dialect A can
understand, the more likely S.I.L. linguists will say that A and B need two
Bibles, not one. The entry for the Chadian language of Bernde, for example,
rates its similarity to its six neighboring languages from 47 to 73 percent.
Above 70 percent, two varieties will typically be called dialects of the same
language.

However, such tests are not always clear-cut. Unintelligible dialects are
sometimes combined into one language if they share a literature or other
cultural heritage. And the reverse can be true, as in the case of Danish and
Norwegian.

In Guatemala, Ethnologue counts 54 living languages, while other linguists,
some of them native Mayan speakers, count 18. Yet undercounting can be just as
political as overcounting.

Colette Grinevald, a specialist in Latin American languages at Lumiere
University in Lyon, France, notes that the modern Maya political movement wants
to unite under one language, Kaqkchikel. ''They don't want that division of
their language into 24 languages,'' she said. ''They want to create a standard
called Kaqkchikel.''

Beyond its political implications, the Ethnologue also carries the weight
of a religious mission. The project was founded by Richard Pittman, a missionary
who thought other missionaries needed better information about which languages
lacked a Bible. The first version appeared in 1951, 10 mimeographed pages that
described 40 languages.

''Hardly anyone knew about the Ethnologue back then,'' said Barbara Grimes,
who edited the survey from 1967 to 2000. ''It was a good idea, but it wasn't
very impressive.'' In 1971, Ms. Grimes and her husband, Joseph Grimes, a
linguistics professor at Cornell, extended the survey from small languages to
all languages in the world.

What emerged was just how daunting a global Bible translation project was.
''In 1950, when we joined S.I.L., we were telling each other, maybe there are
about 1,000 languages, but nobody really knew,'' Ms. Grimes said. In 1969,
Ethnologue listed 4,493 languages; in 1992, the number had risen to 6,528 and by
2000 it stood at 6,809.

The number will probably continue to rise -- 2,694 languages still need to
be studied in detail, and in 2000, S.I.L. officials projected that at the
current rate of work, a complete survey would not be completed until 2075. (They
now say they are working to speed it up.) As for their goal of translating the
Bible, Ethnologue's figures show that all or some of it is available in 2,422
languages.

Ethnologue lists 414 languages as nearly extinct in 2000, a figure that
rises to 497 in the new edition.

However, a few linguists accuse the publisher of promoting the trends it
says it want to prevent. Denny Moore, a linguist with the Goeldi Museum in
Belem, Brazil, said via e-mail: ''It is absurd to think of S.I.L. as an agency
of preservation, when they do just the opposite. Note that along with the
extermination of native religion, all the ceremonial speech forms, songs, music
and art associated with the religion disappear too.''

Dr. Moore, who won a MacArthur ''genius'' grant in 1999 for his 18 years of
linguistic work in Brazil, adds: ''There is no way to resolve this
contradiction. The only options are fooling yourself about it or not.''

S.I.L. officials say missionaries are giving another option to people who
are already experiencing cultural shift. ''The charge of destroying cultures has
been around for a long time,'' said Carol Dowsett, a spokeswoman for the
publisher. ''Basically we're interested in people, and we're interested in
helping them however we can.''

Though the Ethnologue is intended to help spread the word of God, it is
being mined for more secular reasons. Computer companies that are developing
multilingual software for foreign markets turn to the Ethnologue.

''You've got a developer in Silicon Valley, and a person in the field calls
them and says, 'We need to provide support for Serbian' or some language the
developer's never heard of, so they can pop open the Ethnologue and find out,
'What is this thing?''' says Peter Constable, a former S.I.L. linguist who now
works at Microsoft.

Ray Gordon, the editor, says producers of ''Who Wants to Be a Millionaire''
once contacted him, and according to Brian Homoleski, the manager of the
publisher's bookstore, several copies were bought after the Sept. 11 attacks by
''a U.S. government agency.'' According to S.I.L. staff members, the American
Bar Association, the Los Angeles Police Department, the New York Olympic
Committee and AT&T all called for help.

Ethnologue's newest step toward worldwide influence has been in the arcane
world of the International Organization of Standards. The survey assigns a
three-letter code to each language (English is ''eng''), and the 7,000-plus
codes (for living and dead languages) is near acceptance in library indexing and
multilingual software standards. The codes also form the backbone of the Open
Language Archives Community, a Web-based technical infrastructure.

Most linguists are unfazed at S.I.L.'s affiliations. ''If you took away all
the literature done by the S.I.L. people done in the last 60 years,'' said Dr.
Ruhlen of Stanford, ''you'd be taking away a lot of language documentation for a
lot of languages for which there's nothing at all.''

CORRECTION-DATE: July 22, 2005

An article in Science Times on Tuesday about the new edition of Ethnologue, a
compendium of the world's languages, used an incorrect ranking of linguistic
diversity, taken from a table in the book. As noted in a chart that accompanied
the article, the nation with the least diversity is North Korea, with one
language, not Haiti, with two.