Clarence Lewis Barnhart (1900–1993) was an American lexicographer best known for editing the Thorndike Century series of graded dictionaries, which were based on word lists and concepts of definition developed by psychological theorist Edward Thorndike. Barnhart subsequently revised and expanded the series and maintained them through the 1980s.
During World War II he undertook the editing of the Dictionary of U.S. Army Terms (TM-20-205) for the War Department. He created the American College Dictionary, published by Random House in 1947, which was later used as the basis of the Random House Dictionary. His three-volume New Century Cyclopedia of Names, published in 1954, was an expansion of the original 1894 volume of the Century Dictionary and Cyclopedia. From the NCCN, he produced the New Century Handbook of English Literature. In the 1950s and 1960s he developed the linguistic approach to reading instruction begun by Leonard Bloomfield entitled Let's Read.
His largest general dictionary was the World Book Dictionary, a two-volume work created as a supplement to the World Book Encyclopedia. It was first published in 1963 and thoroughly revised in 1976, totaling approximately 225,000 individual entries. Consistent with the encyclopedia's use by young people, he wrote definitions which were both simple and accurate, and most entries include sample sentences or phrases. Like Webster's Third New International, it included few proper names, leaving them to be covered by the companion volumes of the encyclopedia.
He also co-edited of the The Barnhart Dictionary of New English Since 1963 (copyright 1973), The Second Barnhart Dictionary of New English (copyright 1980), and The Third Barnhart Dictionary of New English (copyright 1990). These works were designed to cover new words, meanings, and changes in usage. In 1982 he began editing, with his son David, a quarterly publication devoted to thorough dictionary treatment of new words, new meanings and changes in usage entitled The Barnhart Dictionary Companion.
Nearly all of his dictionaries were based heavily upon the collection of evidence the value of which he learned from work he did for Sir William Craigie on the Dictionary of American English at the University of Chicago. Over his career of 64 years he and his staffs accumulated a file of over 7 million quotations exhibiting contemporary usage of English words. He was active in interlinguistics, serving as a consultant to the research body that presented Interlingua in 1951. In the late 20th century he helped, with his son David, to pioneer the use of electronically retrievable evidence from computerized files of news publications.
- Esterhill, Frank, Interlingua Institute: A History. New York: Interlingua Institute, 2000.
- The Barnhart Dictionary Archive (site containing biography and history of dictionaries)