A dictionary is a reference book containing words classed alphabetically and giving information about spelling, etymology, connotation, regional use, equivalent words and phrases in other languages, recommended use or criticized use. Dictionaries are commonly used by language specialists such as writers and translators and also by the general public. Dictionary can have a general purpose and be comprehensive or have a narrower scope such as slang, rhymes or images (visual dictionary).
- In the 1st century, Greeks wrote list of words that had changed over time.
- In the 2nd century, Julius Pollux wrote his Onomasticon. In many ways it resembled an encyclopedia. Today, only fragments of this book remain.
- From the Early Middle Ages, bilingual and multilingual dictionaries started to be published in Europe.
- 1746 a group of London booksellers approached Samuel Johnson to write a dictionary; he completed it, almost singled handed, in 1755.
- In 1857, the Philological Society of London planned to take ten years to write a comprehensive dictionary of the English language. This eventually became the Oxford English Dictionary.
- The computer era now makes it possible to use a dictionary on another format than paper either as on-line dictionary and off-line dictionary.
Copyright lasts lasts an authors' life plus fifty years in some countries (e.g. Canada) and seventy years or longer in others. Once copyright expires, the work is in the Public Domain and may be reused or republished without copyright infringement. This is why many older works are available (e.g. the 1913 Webster) or being made available by volunteer groups such as Project Gutenberg's Distributed Proofreaders.