The source I like is http://www.websters-online-dictionary.org (link below). It has references to word origins, synonyms, usage etc. Jane Austen is quoted quite often under "Use in literature". Entry "persuasion" ( http://www.websters-online-dictionary.org/definition/persuasion ) actually has a quote from "Emma"!
Here is from the entry "lunch":
Lunch is a meal that is taken at noon or in the early afternoon. The term is short for "luncheon". Lunch is sometimes called "dinner" in Great Britain and parts of the United States and Canada.