A common error in students' academic writing is dealt with at The dictionary.
- In this Guide, the emphasis is on monoglot (single-language) dictionaries of English. Bilingual dictionaries are probably commoner in the world as a whole. See such websites as http://yourdictionary.com/ for a selection.
The most authoritative Dictionary for the English language is the Oxford English Dictionary (OED), an immense work of scholarship. (The 2nd edition (1989), the last to be printed, runs to 20 volumes, containing some 231,100 main entries. The third edition is available on-line at http://dictionary.oed.com/ and on CD-ROM.) An extensive family of Oxford Dictionaries - the two-volume Shorter Oxford English Dictionary (SOD), and various single volume dictionaries more suited to student pockets, the Concise, Compact and so on, has been derived from this same database.
Other highly reputable one-volume dictionaries that have been published in the UK include those from the publishers Chambers, Collins, Longmans and Penguin, and one from the Times newspaper group. For pronunciation, there are Dictionaries that concentrate on how to say a word rather than what it means, such as Daniel Jones' English Pronouncing Dictionary (14th ed, ed. Gimson, CUP 1991) and the Longman Pronouncing Dictionary (Wells, Longman 2000). There are also many specialist dictionaries for given subject areas like Archaeology, Economics and Medicine.
For academic purposes, it is best always to refer to OED if possible. But this is a very complex book to use for day-to-day purposes, and students who simply want to look up a word, check a spelling, or find out how to say it are recommended to use a single-volume Dictionary. Which one to use is a matter of personal taste and habit. For those who are learning English as a second - or other - language, there is much to be said for the COBUILD English Language Dictionary published by Collins. (COBUILD stands for 'Collins/Birmingham University International Language Database'.) This one-volume dictionary gives carefully considered advice on how words are actually used, which is extremely useful for non-native speakers. Native speakers will often benefit from this, but do not need this guidance as much as others.
American English is perhaps best served by the Merriam-Webster series of Dictionaries; and many dictionaries for other varieties of the language are available, both on line and in bookshops. These include dictionaries of regional varieties - Australian, Scottish, etc - as well as dictionaries for different registers of the language - slang, colloquialisms and so on.
See also dictionaries - history.