CIA Library: English as a Second Language (ESL): Online Resources

Online Dictionaries

Oxford English Dictionary This link opens in a new window
Widely regarded as the accepted authority on the English language. It is an unsurpassed guide to the meaning, history, and pronunciation of 600,000 words past and presentfrom across the English-speaking world.

Dictionary.com
Dictionary.com is the world’s leading digital dictionary. They provide millions of English definitions, spellings, audio pronunciations, example sentences, and word origins. Dictionary.com’s main, proprietary source is the Random House Unabridged Dictionary, which is continually updated by our team of experienced lexicographers and supplemented with trusted, established sources including American Heritage and Harper Collins to support a range of language needs.
Longman Dictionary of Contemporary English
Clear definitions written using only 2000 common words. Signposts guide you to the right meaning, fast! Instant pop-up dictionary for the web or email.
Miram-Webster's Learner's Dictionary
Clear and simple definitions in basic American English from North America's leading language experts. More usage examples than any other dictionary.