Oxford Dictionaries Online is an English language online
dictionary. In addition to definitions it includes synonyms and
antonyms, sample sentences, audio pronunciations; writing,
grammar and spelling guidance.
The Oxford English Dictionary is the authority on the
English language. It is a complete guide to the meaning, history,
and pronunciation of 600,000 words— past and present—from across
the English-speaking world. The history of individual
words, and of the language—traced through 3 million quotations,
from classic literature and specialist periodicals to films
scripts and cookery books is all available in this dictionary.
Grolier Online includes both the Americana Encyclopedia (which is
appropriate for high-school students and beyond) and Grolier
Multimedia Encyclopedia (which is suitable for middle-school and
high-school students).