To find the meaning of a legal term, look in a legal dictionary. The standard legal dictionary in the U.S. is Black's Law Dictionary. Copies are available on the dictionary stand in the middle of the Reading Room, in the Reference shelves in the Reading Room, and on a table in the F/I Reading Room.

Black's Law Dictionary, 7th ed. (KF156 .B53 1999) also on Westlaw (database "blacks")
If you find Black's too difficult to understand (it frequently uses legal terminology in its definitions), you might try a law dictionary intended for non-specialists. There are many in the Reference section of the Reading Room. Here are some titles:

Brann, The Law Dictionary, 7th ed.
(KF156 .C6 1997)
Garner, A Handbook of Basic Law Terms
(KF156 .H359 1999)
Gifis, Dictionary of Legal Terms, 3rd ed.
(KF156 .G527 1998)
Hill & Hill, Real Life Dictionary of the Law
(KF156 .H55 1995)also on the Web at dictionary.law.com
Oran, Law Dictionary for Nonlawyers, 3rd ed.
(KF156 .O7 1991)
Merriam-Webster's Dictionary of Law (1996)
on the Web at dictionary.lp.findlaw.com

For more detailed definitions that have been adopted by courts, see Words and Phrases, a multi-volume dictionary with definitions drawn from judicial opinions. It is shelved in the Reference section of the Reading Room.

Words and Phrases (KF156 .W6712)
The Goldman Library also has many bilingual law dictionaries. Here are a few examples. The most commonly used are shelved together in the F/I Reference collection on L1.

Chinese: Dictionary of law, English-Chinese. (K52.C5 D53 1999)
French: Dahl's law dictionary : French to English/English to French (K52.F7 D35 1995)
German: Dietl, Worterbuch fur Recht, Wirtschaft und Politik (K52.G4 D5 1987)
Italian: Dizionario giuridico (K52. I73 D4 1984)
Spanish: West's Spanish-English/English-Spanish law dictionary (K52.S6 S65 1992)