The American Heritage Dictionary (1969 original; edició 1980)

As an older edition, this is unlikely to be bought very widely, but I'll pass along a snippet I read in a historical review of the publication, which is that the justly-renowned "usage panel" was at a low ebb for this edition. Earlier and later editions are better for that useful feature. ( )

One of the things I like about this dictionary in addition to the usage panel are the excellent pictures. ( )

A solid dictionary, with thorough coverage of obscure words and etymologies. ( )

The thing I like most about the American Heritage Dictionary is the Usage panel approach, in which a highly literate panel of experts votes on the appropriateness of a particular usage. To be sure, English is an evolving language. That is not to say that we simply hold our standard of speech to an all-accepting level simply because the common man has started to talk in a particular way; after all, good grammar and usage are not about being understood, they are about being understood to be educated.

The usage panel deals with the evolution of language by putting questionable usages to a vote among a group of people whom most users of dictionaries would aspire to be on a par with. ( )

This edition is very special to me because it was awarded by the state of Kansas, and I'm proud to come from a state that gives dictionaries to its honor students. Yes, it includes the word "evolution."