Longman Dictionary of Contemporary English
Cambridge Dictionary
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Collins Dictionary
Dictionary.com
The American heritage dictionary of the English language
Merriam-Webster
Macmillan Dictionaries
ozdic.com Collocation Dictionary
COCA – Corpus of Contemporary American English
W. W. Skeat, An etymological dictionary of the English language
E. Weekley, An etymological dictionary of Modern English
Online Etymology Dictionary
The historical thesaurus of English
S. Johnson, A dictionary of the English language
Middle English Dictionary
Bosworth Toller’s Anglo-Saxon dictionary online
Anglo-Norman Dictionary
A thesaurus of Old English
H. Yule, A. C. Burnell, Hobson-Jobson. A glossary of colloquial Anglo-Indian words and phrases, and of kindred terms, etymological, historical, geographical and discursive
Jewish English lexicon
Encyclopædia Britannica
Brewster’s Dictionary of phrase & fable