What is the authorative dictionary for the United States?

Question

eg: the Oxford Dictionary is the authorative dictionary for the United Kingdom.
I am talking about dictionaries that come in about 20 volumes.
I want to know so I can look up the definition of a legal term.

Answer 1

There are two main dictionaries at the top of the heap, though not quite the length you are looking for! (We too use the OED if we're looking for that kind of detail.) You'll find them in most libraries, and are at worth

Webster's Third New International Dictionary, Unabridged (published by Merriam Webster) [there is also the "Random House Webster's Unabridged Dictionary"].

American Heritage (not unabridged, by very good and my personal favorite for most ordinary needs)

You may find, in any case, that you need some sort of specialty dictionary for what you're after. Perhaps, if it's not TOO obscure, you can find it with something like:
http://dictionary.law.com/
http://www.law-dictionary.org/

Or try this site, which links to online law dictionaries (a number of them free) AND tells you about hardcover editions
http://www.lawdictionaries.com/

Answer 2

Websters

Answer 3

I don't believe there is one really. Several different companies make them.

But the American language is a living breathing entity that slowly changes over time. New definitions sometimes get added to old words as they get used in unique or different ways. Old words fall out of usage or new words crop up.

Like "Truthiness"

Answer 4

A Webster's unabridged should do just fine.