In legal terms, a “liber" is a book of public records such as deeds, birth certificates, and death certificates. In real estate law, a liber is used to indicate ownership of property such as land and buildings. In American law, liber is most commonly pronounced “lahy-ber." In the classical period of Latin, this word is pronounced “lee-bear."
One of the difficulties of learning any language is in pronouncing words not as one would in one’s own language, but as a native speaker of the foreign language. Luckily for the Latin student, pronunciation in Latin is far less complex than English. However, “liber" does produce one complexity that most Latin students find perplexing.
Although spelled identically, liber (pronounced “lee-bear") meaning “book" and liber (pronounced “lib-air") meaning “free" are declined using different conventions. Liber (book) declines in the singular as “liber, libri, libro, librum, libro" while liber (free) declines as “liber, liberi, libero, liberum, libero." To help remember this distinction, recall that the word liber (book) is the derivative of our word “library" and is therefore declined with a long “i." Liber (free) is the derivative of our word “liberty" and is therefore declined with a short “i." Some Latin programs make use of macrons (ī, līber) to help indicate when vowels are long and short. Absent this indicator, the Latin student must rely on context, experience, and declension memorization to properly translate a given word.