• Oxford OALD: "Oxford Advanced Learner's Dictionary is a popular dictionary published by the Oxford University Press. It is a monolingual learner's dictionary, aimed at advanced learners of English as a second language all over the world." -> bof
  • Oxford Compact: Compact Oxford English Dictionary
  • Chambers Harrap: "The tenth edition of the Chambers Dictionary of the English language was published in 2006 by Chambers Harrap. Originally published in 1901 as Chambers's Twentieth Century Dictionary, the dictionary is widely used by British crossword solvers and setters, and by Scrabble players." -> bof
  • Collins: Collins is still used as an imprint, chiefly for wildlife and natural history books (including the on-going New Naturalist series) and field guides, as well as English and bilingual dictionaries based on the Bank of English, a large corpus of contemporary English texts.
  • Cambridge: Cambridge Advanced Learner's Dictionary -> bof
  • Merriam Webster: "Merriam-Webster, originally known as the G. & C. Merriam Company of Springfield, Massachusetts, is a United States company that publishes reference books, especially dictionaries that are descendants of Noah Webster's An American Dictionary of the English Language (1828)."
  • American Heritage: "The American Heritage Dictionary of the English Language is an American dictionary of the English language published by Boston publisher Houghton-Mifflin, the first edition of which appeared in 1969." -> bof
  • Ultralingua -> inconnu au bataillon
  • Wordsmyth children -> inconnu au bataillon

Conclusion: fouiller dans l'Oxford English Dictionary (payant, mais définitivement la référence) ou le Merriam-Webster (c'est un synonyme de "dictionnaire" en Amérique...).