Black's Law Dictionary, 4th Edition
Most genealogists need to learn some basic legal terms in order to understand their ancestors’ deeds and court cases. Many of the legal terms defined in this encyclopedia were derived in part from Black's Law Dictionary, Fourth Edition, now long out of print. Why that edition? Because it was the last edition that includes all the old, English common law terms that our colonial ancestors used, and are particularly important to U. S. genealogists. A few copies of the fourth edition may still be found on the used book market.
Source: Henry Campbell Black, Black's Law Dictionary, Fourth Edition (St. Paul:1951), West Publishing Co.